mk/efi.mk: Disable stack protector

Disable the stack protector if on by default.

Copied from https://bugs.gentoo.org/show_bug.cgi?id=495146.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
efi: We need -m32/-m64 even when processing assembly

We need to specify -m32/-m64 even when we are processing assembly.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Makefile: make "make spotless" actually work

The other cleaning targets might still have issues...

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>