i386: Check -mindirect-branch/-mfunction-return with -fcf-protection

i386: Check -mindirect-branch/-mfunction-return with -fcf-protection

Issue an error when -mindirect-branch or -mfunction-return are used
with incompatible -fcf-protection.

gcc/

	PR target/87412
	* config/i386/i386.c (ix86_set_indirect_branch_type): Issue an
	error for -mindirect-branch/-mfunction-return with incompatible
	-fcf-protection.

gcc/testsuite/

	PR target/87412
	* gcc.target/i386/pr87412-1.c: New file.
	* gcc.target/i386/pr87412-2.c: Likewise.
	* gcc.target/i386/pr87412-3.c: Likewise.
	* gcc.target/i386/pr87412-4.c: Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@269068 138bc75d-0d04-0410-961f-82ee72b054a4