Rebase to FSF GDB 13.1.
Update gdb-6.3-rh-testversion-20041202.patch.
Update gdb-6.3-bz140532-ppc-unwinding-test.patch.
Update gdb-6.6-buildid-locate.patch.
Update gdb-6.6-buildid-locate-rpm.patch.
Remove 'Recommends: ' line for gcc-gdb-plugin for BZ2149246.
Add 'define _lto_cflags %{nil}' to avoid ODR violations.