Ada: Remove debug line number for DECL_IGNORED_P functions

Ada: Remove debug line number for DECL_IGNORED_P functions

It was pointed out in PR101598 to be inappropriate, that
ignored Ada decls receive the source line number which was
recorded in the function decl's DECL_SOURCE_LOCATION.
Therefore set all front-end-generated Ada decls with
DECL_IGNORED_P to UNKNOWN_LOCATION.

2021-08-11  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	PR debug/101598
	* gcc-interface/trans.c (Subprogram_Body_to_gnu): Set the
	DECL_SOURCE_LOCATION of DECL_IGNORED_P gnu_subprog_decl to
	UNKNOWN_LOCATION.