libgfortran: Small progress on the library side

The following patch quiets
../../../libgfortran/generated/in_pack_r17.c:35:1: warning: no previous prototype for ‘internal_pack_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/in_pack_c17.c:35:1: warning: no previous prototype for ‘internal_pack_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/in_unpack_r17.c:33:1: warning: no previous prototype for ‘internal_unpack_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/in_unpack_c17.c:33:1: warning: no previous prototype for ‘internal_unpack_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/pack_r17.c:73:1: warning: no previous prototype for ‘pack_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/pack_c17.c:73:1: warning: no previous prototype for ‘pack_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/unpack_r17.c:34:1: warning: no previous prototype for ‘unpack0_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/unpack_r17.c:178:1: warning: no previous prototype for ‘unpack1_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/unpack_c17.c:34:1: warning: no previous prototype for ‘unpack0_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/unpack_c17.c:178:1: warning: no previous prototype for ‘unpack1_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/spread_r17.c:34:1: warning: no previous prototype for ‘spread_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/spread_r17.c:230:1: warning: no previous prototype for ‘spread_scalar_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/spread_c17.c:34:1: warning: no previous prototype for ‘spread_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/spread_c17.c:230:1: warning: no previous prototype for ‘spread_scalar_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift0_r17.c:33:1: warning: no previous prototype for ‘cshift0_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift0_c17.c:33:1: warning: no previous prototype for ‘cshift0_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift1_4_r17.c:32:1: warning: no previous prototype for ‘cshift1_4_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift1_4_c17.c:32:1: warning: no previous prototype for ‘cshift1_4_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift1_8_r17.c:32:1: warning: no previous prototype for ‘cshift1_8_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift1_8_c17.c:32:1: warning: no previous prototype for ‘cshift1_8_c17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift1_16_r17.c:32:1: warning: no previous prototype for ‘cshift1_16_r17’ [-Wmissing-prototypes]
../../../libgfortran/generated/cshift1_16_c17.c:32:1: warning: no previous prototype for ‘cshift1_16_c17’ [-Wmissing-prototypes]
warnings during libgfortran build and exports the new entrypoints.
Note, not all of them, clearly e.g. there are fewer *_r17* entrypoints than
*_r16* entrypoints, so more work is needed.

2021-12-31  Jakub Jelinek  <jakub@redhat.com>

	* libgfortran.h (internal_pack_r17, internal_pack_c17,
	internal_unpack_r17, internal_unpack_c17, pack_r17, pack_c17,
	unpack0_r17, unpack0_c17, unpack1_r17, unpack1_c17, spread_r17,
	spread_c17, spread_scalar_r17, spread_scalar_c17, cshift0_r17,
	cshift0_c17, cshift1_4_r17, cshift1_8_r17, cshift1_16_r17,
	cshift1_4_c17, cshift1_8_c17, cshift1_16_c17): Declare.
	* gfortran.map (GFORTRAN_12): Export *_r17 and *_c17.