PR fortran/63797 - Bogus ambiguous reference to 'sqrt'

The interface of an intrinsic procedure is automatically explicit.
Do not write it to the module file to prevent wrong ambiguities on USE.

gcc/fortran/ChangeLog:

	PR fortran/63797
	* module.c (write_symtree): Do not write interface of intrinsic
	procedure to module file for F2003 and newer.

gcc/testsuite/ChangeLog:

	PR fortran/63797
	* gfortran.dg/pr63797.f90: New test.

Co-authored-by: Paul Thomas <pault@gcc.gnu.org>