PR modula2/115823 Wrong expansion of isnormal optab

PR modula2/115823 Wrong expansion of isnormal optab

This patch corrects the function declaration of a builtin
(using the libname rather than the source name).

gcc/m2/ChangeLog:

	PR modula2/115823
	* gm2-gcc/m2builtins.cc (define_builtin): Build
	the function decl using the libname.

gcc/testsuite/ChangeLog:

	PR modula2/115823
	* gm2/builtins/run/pass/testisnormal.mod: Change to an
	implementation module.
	* gm2/builtins/run/pass/testisnormal.def: New test.
	* gm2/builtins/run/pass/testsinl.def: New test.
	* gm2/builtins/run/pass/testsinl.mod: New test.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>