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.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>