lcm: add missing pkgconfig inherit

This fixes:

| autoreconf: running:
/build/scratch/angstrom-v2014.12/build/tmp-angstrom_next-eglibc/sysroots/x86_64-linux/usr/bin/autoconf
--include=/build/scratch/angstrom-v2014.12/build/tmp-angstrom_next-eglibc/work/armv5te-angstrom-linux-gnueabi/lcm/1.0.0-r0/lcm-1.0.0/m4/
--include=/build/scratch/angstrom-v2014.12/build/tmp-angstrom_next-eglibc/work/armv5te-angstrom-linux-gnueabi/lcm/1.0.0-r0/lcm-1.0.0/m4macros/
--force
| configure.in:9: error: possibly undefined macro: AC_MSG_ERROR
|       If this token and others are legitimate, please use
m4_pattern_allow.

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>