*: Fix build with recent gcc/binutils

*: Fix build with recent gcc/binutils

With current Debian testing I get:

	tools/ccanlint/ccanlint -s --deps-fail-ignore   ccan/compiler/ && touch ccan/compiler/.ok
	compiler: Module tests compile (tests_compile): FAIL
	/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/ccan/compiler/test/run-is_compile_constant.c:Compile failed:
	/usr/bin/ld: /tmp/ccanlint-129350.1804289383/tap.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/ccan/tap/tap.h:249: multiple definition of `tap_fail_callback'; /tmp/ccrAwqbl.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/ccan/tap/tap.h:249: first defined here
	collect2: error: ld returned 1 exit status
	...

	cc -g3 -ggdb -Wall -Wstrict-prototypes -Wold-style-definition -Wundef -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith -Wwrite-strings -DCCAN_STR_DEBUG=1 -I.  -MMD -MP -MFtools/ccanlint/ccanlint.d -MTtools/ccanlint/ccanlint tools/ccanlint/ccanlint.c tools/ccanlint/async.o tools/ccanlint/file_analysis.o tools/ccanlint/licenses.o tools/ccanlint/tests/avoids_cpp_reserved.o tools/ccanlint/tests/depends_accurate.o tools/ccanlint/tests/depends_build.o tools/ccanlint/tests/depends_build_without_features.o tools/ccanlint/tests/depends_exist.o tools/ccanlint/tests/examples_compile.o tools/ccanlint/tests/examples_exist.o tools/ccanlint/tests/examples_relevant.o tools/ccanlint/tests/examples_run.o tools/ccanlint/tests/hash_if.o tools/ccanlint/tests/headers_idempotent.o tools/ccanlint/tests/info_compiles.o tools/ccanlint/tests/info_documentation_exists.o tools/ccanlint/tests/info_exists.o tools/ccanlint/tests/info_ported.o tools/ccanlint/tests/info_summary_single_line.o tools/ccanlin
 t/tests/license_comment.o tools/ccanlint/tests/license_depends_compat.o tools/ccanlint/tests/license_exists.o tools/ccanlint/tests/license_file_compat.o tools/ccanlint/tests/main_header_compiles.o tools/ccanlint/tests/main_header_exists.o tools/ccanlint/tests/module_builds.o tools/ccanlint/tests/module_links.o tools/ccanlint/tests/no_trailing_whitespace.o tools/ccanlint/tests/objects_build.o tools/ccanlint/tests/objects_build_with_stringchecks.o tools/ccanlint/tests/objects_build_without_features.o tools/ccanlint/tests/reduce_features.o tools/ccanlint/tests/tests_compile.o tools/ccanlint/tests/tests_compile_coverage.o tools/ccanlint/tests/tests_coverage.o tools/ccanlint/tests/tests_exist.o tools/ccanlint/tests/tests_helpers_compile.o tools/ccanlint/tests/tests_pass.o tools/ccanlint/tests/tests_pass_valgrind.o tools/ccanlint/tests/tests_pass_without_features.o ccan/autodata/autodata.o ccan/dgraph/dgraph.o ccan/ilog/ilog.o ccan/lbalance/lbalance.o ccan/ptr_valid/ptr_valid.o ccan/strma
 p/strmap.o tools/ccan_dir.o tools/compi
	le.o tools/depends.o tools/doc_extract-core.o tools/gcov.o tools/manifest.o tools/read_config_header.o tools/tools.o ccan/asort/asort.o ccan/err/err.o ccan/foreach/foreach.o ccan/hash/hash.o ccan/htable/htable.o ccan/list/list.o ccan/membuf/membuf.o ccan/noerr/noerr.o ccan/opt/helpers.o ccan/opt/opt.o ccan/opt/parse.o ccan/opt/usage.o ccan/rbuf/rbuf.o ccan/read_write_all/read_write_all.o ccan/str/debug.o ccan/str/str.o ccan/take/take.o ccan/tal/tal.o ccan/tal/grab_file/grab_file.o ccan/tal/link/link.o ccan/tal/path/path.o ccan/tal/str/str.o ccan/time/time.o -lm -o tools/ccanlint/ccanlint
	/usr/bin/ld: tools/ccanlint/async.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: multiple definition of `license_compatible'; /tmp/cc72h7qq.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: first defined here
	/usr/bin/ld: tools/ccanlint/file_analysis.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: multiple definition of `license_compatible'; /tmp/cc72h7qq.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: first defined here
	/usr/bin/ld: tools/ccanlint/licenses.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/licenses.h:33: multiple definition of `license_compatible'; /tmp/cc72h7qq.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: first defined here
	/usr/bin/ld: tools/ccanlint/tests/avoids_cpp_reserved.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/./tools/ccanlint/../ccanlint/licenses.h:33: multiple definition of `license_compatible'; /tmp/cc72h7qq.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: first defined
	here
	/usr/bin/ld: tools/ccanlint/tests/depends_accurate.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/./tools/ccanlint/../ccanlint/licenses.h:33: multiple definition of `license_compatible'; /tmp/cc72h7qq.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: first defined here
	/usr/bin/ld: tools/ccanlint/tests/depends_build.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/./tools/ccanlint/../ccanlint/licenses.h:33: multiple definition of `license_compatible'; /tmp/cc72h7qq.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: first defined here
	/usr/bin/ld: tools/ccanlint/tests/depends_build_without_features.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/./tools/ccanlint/../ccanlint/licenses.h:33: multiple definition of `license_compatible'; /tmp/cc72h7qq.o:/home/kirr/src/wendelin/wendelin.core/3rdparty/ccan/tools/ccanlint/../ccanlint/licenses.h:33: first defined here
	...

The errors are valid becuase symbols are declared without extern in .h
files and those .h files are included from multiple translation units.

-> Fix it. I'm not sure why it used to compile ok before.

Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
Message-Id: <20200910191610.131510-1-kirr@nexedi.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>