fortran: Correctly evaluate scalar MASK arguments of MINLOC/MAXLOC

fortran: Correctly evaluate scalar MASK arguments of MINLOC/MAXLOC

Add the preliminary code that the generated expression for MASK may depend
on when generating the inline code to evaluate MINLOC or MAXLOC with a
scalar MASK.

The generated code was only keeping the generated expression but not the
preliminary code, which was sufficient for simple cases such as data
references or simple (scalar) function calls, but was bogus with more
complicated ones.

gcc/fortran/ChangeLog:

	* trans-intrinsic.cc (gfc_conv_intrinsic_minmaxloc): Add the
	preliminary code generated for MASK to the preliminary code of
	MINLOC/MAXLOC.

gcc/testsuite/ChangeLog:

	* gfortran.dg/minmaxloc_17.f90: New test.