valgrind locally complains about the allocations in autodata leaking:
```
==138200== 16 bytes in 1 blocks are still reachable in loss record 1 of 2
==138200== at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==138200== by 0x10D41A: autodata_register_ (autodata.c:20)
==138200== by 0x10E7B8: register_autotype_type_to_string (type_to_string.h:79)
==138200== by 0x10F5CA: register_one_type_to_string0 (block.c:259)
==138200== by 0x19734C: __libc_csu_init (in /home/rusty/devel/cvs/lightning/common/test/run-route-specific)
==138200== by 0x4A3D03F: (below main) (libc-start.c:264)
==138200==
==138200== 176 bytes in 1 blocks are still reachable in loss record 2 of 2
==138200== at 0x483DFAF: realloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==138200== by 0x10D472: autodata_register_ (autodata.c:26)
==138200== by 0x122D37: register_autotype_type_to_string (type_to_string.h:79)
==138200== by 0x122F1F: register_one_type_to_string0 (node_id.c:50)
==138200== by 0x19734C: __libc_csu_init (in /home/rusty/devel/cvs/lightning/common/test/run-route-specific)
==138200== by 0x4A3D03F: (below main) (libc-start.c:264)
==138200==
make: *** [Makefile:638: unittest/common/test/run-route-specific] Error 7
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
68043c2e8c