PR c/89946

	PR c/89946
	* varasm.c (assemble_start_function): Don't use tree_fits_uhwi_p
	and gcc_unreachable if it fails, just call tree_to_uhwi which
	verifies that too.  Test TREE_CHAIN instead of list_length > 1.
	Start warning message with a lower-case letter.  Formatting fixes.
c-family/
	* c-attribs.c (handle_patchable_function_entry_attribute): Add
	function comment.  Warn if arguments of the attribute are not positive
	integer constants.
testsuite/
	* c-c++-common/pr89946.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@270305 138bc75d-0d04-0410-961f-82ee72b054a4