PR 15276: Add $_caller_is, $_caller_matches, $_any_caller_is, $_any_caller_matches

PR 15276: Add $_caller_is, $_caller_matches, $_any_caller_is, $_any_caller_matches

gdb/ChangeLog:

	PR 15276
	* NEWS: Mention $_caller_is, $_caller_matches, $_any_caller_is,
	$_any_caller_matches.
	* data-directory/Makefile.in (PYTHON_FILE_LIST): Add caller_is.py.
	* python/lib/gdb/function/caller_is.py: New file.

gdb/testsuite/ChangeLog:

	PR 15276
	* gdb.python/py-caller-is.c: New file.
	* gdb.python/py-caller-is.exp: New file.

gdb/doc/ChangeLog:

	PR 15276
	* gdb.texinfo (Convenience Funs): Document $_caller_is,
	$_caller_matches, $_any_caller_is, $_any_caller_matches.