gcc-configure-target: Add --enable-dependency-tracking to EXTRA_OECONF
Fixes errors seen while compiling gcc 4.8 for target, errors like
| /home/khem/work/angstrom/build/tmp-angstrom_next-eglibc/work-shared/gcc-4.8.0-r0/gcc-4.8.0/libatomic/cas_n.c:125:1: fatal error: opening dependency file .deps/cas_1_.lo.Ppo: No such file or directory
which are due to disabled dependency tracking but dependency files being still generated
while compiling libatomics.
