Remove 2 excessive executable permission flags

Fedora rpmbuild has been complaining:
	*** WARNING: ./usr/src/debug/gdb-8.1.50.20180618-24.fc28.x86_64/gdb/gdbserver/x86-tdesc.h is executable but has empty or no shebang, removing executable bit

gdb/gdbserver/ChangeLog
2018-06-28  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* x86-tdesc.h: Remove executable permission flag.

gdb/testsuite/ChangeLog
2018-06-28  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* lib/compiler.c: Remove executable permission flag.