PR modula2/116918 -fswig correct syntax

This patch fixes the syntax for the generated swig interface file.
The % characters in fprintf require escaping.

gcc/m2/ChangeLog:

	PR modula2/116918
	* gm2-compiler/M2Swig.mod (AnnotateProcedure): Capitalize
	the generated comment, split comment into multiple lines and
	terminate the comment with ".  */".
	(DoCheckUnbounded): Escape the % character with %%.
	(DoWriteFile): Ditto.

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