options: Define TARGET_<NAME>_P and TARGET_<NAME>_OPTS_P macro for Mask and InverseMask

We TARGET_<NAME>_P marcro to test a Mask and InverseMask with user
specified target_variable, however we may want to test with specific
gcc_options variable rather than target_variable.

Like RISC-V has defined lots of Mask with TargetVariable, which is not
easy to use, because that means we need to known which Mask are associate with
which TargetVariable, so take a gcc_options variable is a better interface
for such use case.

gcc/ChangeLog:

	* doc/options.texi (Mask): Document TARGET_<NAME>_P and
	TARGET_<NAME>_OPTS_P.
	(InverseMask): Ditto.
	* opth-gen.awk (Mask): Generate TARGET_<NAME>_P and
	TARGET_<NAME>_OPTS_P macro.
	(InverseMask): Ditto.