libfortran: Fix up _gfortran_s{max,min}loc2_{4,8,16}_s{1,4} [PR120191]

libfortran: Fix up _gfortran_s{max,min}loc2_{4,8,16}_s{1,4} [PR120191]

I've tried to write a testcase for the BT_CHARACTER maxloc/minloc with named
or unnamed arguments and indeed the just posted patch fixed the arguments
in there in multiple cases to match what the library expects.
But the testcase still fails, due to library problems.

One dealt with in this patch are _gfortran_s{max,min}loc2_{4,8,16}_s{1,4}
functions.  Those are trivial wrappers around
_gfortrani_{max,min}loc2_{4,8,16}_s{1,4} which should call those functions
if the scalar mask is true and just return 0 otherwise.
The two bugs I see there is that the back, len arguments are swapped,
which means that it always acts as back=.true. and for len will use
character length of 1 or 0 instead of the desired one.
The _gfortrani_{max,min}loc2_{4,8,16}_s{1,4} functions have prototypes like
GFC_INTEGER_4
maxloc2_4_s1 (gfc_array_s1 * const restrict array, GFC_LOGICAL_4 back, gfc_charlen_type len)
so back comes before len, ditto for the
GFC_INTEGER_4
smaxloc2_4_s1 (gfc_array_s1 * const restrict array,
               GFC_LOGICAL_4 *mask, GFC_LOGICAL_4 back, gfc_charlen_type len)
The other problem is that it was just testing if (mask).  In my limited
Fortran understanding that means that the optional argument mask was
supplied but nothing about its actual value.  Other scalar mask generated
routines use if (mask == NULL || *mask) as the condition when to call the
non-masked function, i.e. when mask is not supplied (then it should act like
.true. mask) or when it is supplied and evaluates to .true.).

2025-05-13  Jakub Jelinek  <jakub@redhat.com>

	PR fortran/120191
	* m4/maxloc2s.m4: For smaxloc2 call maxloc2 if mask is NULL or *mask.
	Swap back and len arguments.
	* m4/minloc2s.m4: Likewise.
	* generated/maxloc2_4_s1.c: Regenerate.
	* generated/maxloc2_4_s4.c: Regenerate.
	* generated/maxloc2_8_s1.c: Regenerate.
	* generated/maxloc2_8_s4.c: Regenerate.
	* generated/maxloc2_16_s1.c: Regenerate.
	* generated/maxloc2_16_s4.c: Regenerate.
	* generated/minloc2_4_s1.c: Regenerate.
	* generated/minloc2_4_s4.c: Regenerate.
	* generated/minloc2_8_s1.c: Regenerate.
	* generated/minloc2_8_s4.c: Regenerate.
	* generated/minloc2_16_s1.c: Regenerate.
	* generated/minloc2_16_s4.c: Regenerate.

	* gfortran.dg/pr120191_2.f90: New test.