gdb-cross: fix issue where patch has already been applied to 6.6

gdb-cross: fix issue where patch has already been applied to 6.6
gdb-cross version 6.6 fails the patch process because the sim-install.patch
tries to apply patches to Makefile-common which have already been merged into
gdm mainstream.
Attached is a patch for OE that seperates the two patches in sim-install.patch
so that gdb-cross 6.6 only applies the first one while gdb-cross 6.3 (which
also uses the sim-install.patch applies both.