jmap: fix tools/speed

jmap: fix tools/speed

Minor fixes on top of patch from rocco@tecsiel.it:

Hi Rusty,
latest git version of the file ccan/jmap/tools/speed.c does not
compile.

Please find attacched my own version with the following differences:

  1. deleted inclusion of <ccan/jmap/jmap_type.h> which is no longer in ccan/

  2. added inclusion of <ccan/time/time.h>

  3. added definition of struct jmap_obj in terms of JMAP_MEMBERS();

  4. deleted use of macro JMAP_DEFINE_UINTIDX_TYPE() which is no longer needed

  5. changed function normalize() to be aligned with ccan/htable/tools/speed.c

  6. repleaced gettimeofday() in favour of time_now()

  7. added memory cleanup at the end of the program in terms of
       jmap_free(jmap);
       free(objs);
     to be valgrind safe

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>