Add default_promote_function_mode_sign_extend

Add default_promote_function_mode_sign_extend

TARGET_PROMOTE_PROTOTYPES is an optimization, not an ABI requirement.
TARGET_PROMOTE_FUNCTION_MODE should be used for ABI requirement.  Like
xtensa, mcore ABI requires sign extension of signed 8/16-bit integer
arguments to 32 bits and zero extension of unsigned integer 8/16-bit
arguments to 32 bits:

1. Rename xtensa_promote_function_mode to
default_promote_function_mode_sign_extend to sign-extend signed 8/16-bit
integer arguments to 32 bits and zero-extend of unsigned 8/16-bit
integer arguments to 32 bits.
2. Replace xtensa_promote_function_mode with
default_promote_function_mode_sign_extend.
3. Remove TARGET_PROMOTE_PROTOTYPES for mcore and define
TARGET_PROMOTE_FUNCTION_MODE with
default_promote_function_mode_sign_extend to properly extend 8/16-bit
arguments to 32 bits.

Targets with the same ABI requirement should define
TARGET_PROMOTE_FUNCTION_MODE with
default_promote_function_mode_sign_extend.

gcc/

	PR target/119979
	PR target/120888
	* targhooks.cc (default_promote_function_mode_sign_extend): New.
	* targhooks.h (default_promote_function_mode_sign_extend):
	Likewise.
	* config/mcore/mcore.cc (TARGET_PROMOTE_FUNCTION_MODE): Use
	default_promote_function_mode_sign_extend.
	(TARGET_PROMOTE_PROTOTYPES): Removed.
	* config/xtensa/xtensa.cc (xtensa_promote_function_mode): Removed.
	(TARGET_PROMOTE_FUNCTION_MODE): Use
	default_promote_function_mode_sign_extend.

gcc/testsuite/

	PR target/119979
	PR target/120888
	* gcc.target/xtensa/pr120888-1.c: Removed to ...
	* gcc.dg/zero-extend.c: This.  Enable for mcore and xtensa.
	* gcc.target/xtensa/pr120888-2.c: Removed to ...
	* gcc.dg/sign-extend.c: This.  Enable for mcore and xtensa.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>