c-family: copy attribute diagnostic fixes [PR113262]

c-family: copy attribute diagnostic fixes [PR113262]

The copy attributes is allowed on decls as well as types and even has
checks whether decl (set to *node) is DECL_P or TYPE_P, but for diagnostics
unconditionally uses DECL_SOURCE_LOCATION (decl), which obviously only works
if it applies to a decl.

2024-01-09  Jakub Jelinek  <jakub@redhat.com>

	PR c/113262
	* c-attribs.c (handle_copy_attribute): Don't use
	DECL_SOURCE_LOCATION (decl) if decl is not DECL_P, use input_location
	instead.  Formatting fixes.

	* gcc.dg/pr113262.c: New test.

(cherry picked from commit c9fc7f398e8b330ff12ec8a29bfa058b6daf6624)