Fix one issue in OpenMP 'requires' directive diagnostics

Fix one issue in OpenMP 'requires' directive diagnostics

Fix-up for recent commit 683f11843974f0bdf42f79cdcbb0c2b43c7b81b0
"OpenMP: Move omp requires checks to libgomp".

	gcc/
	* lto-cgraph.cc (input_offload_tables) <LTO_symtab_edge>: Correct
	'fn2' computation.
	libgomp/
	* testsuite/libgomp.c-c++-common/requires-1.c: Add 'dg-note's.
	* testsuite/libgomp.c-c++-common/requires-2.c: Likewise.
	* testsuite/libgomp.c-c++-common/requires-3.c: Likewise.
	* testsuite/libgomp.c-c++-common/requires-7.c: Likewise.
	* testsuite/libgomp.fortran/requires-1.f90: Likewise.

(cherry picked from commit faa0c328ee65f0d6d65d6e20181d26e336071919)