analyzer: fix direction of -Wanalyzer-out-of-bounds note [PR106626]

analyzer: fix direction of -Wanalyzer-out-of-bounds note [PR106626]

Fix a read/write typo.

Also, add more test coverage of -Wanalyzer-out-of-bounds to help
establish a baseline for experiments on tweaking the wording of
the warning (PR analyzer/106626).

gcc/analyzer/ChangeLog:
	PR analyzer/106626
	* region-model.cc (buffer_overread::emit): Fix copy&paste error in
	direction of the access in the note.

gcc/testsuite/ChangeLog:
	PR analyzer/106626
	* gcc.dg/analyzer/out-of-bounds-read-char-arr.c: New test.
	* gcc.dg/analyzer/out-of-bounds-read-int-arr.c: New test.
	* gcc.dg/analyzer/out-of-bounds-write-char-arr.c: New test.
	* gcc.dg/analyzer/out-of-bounds-write-int-arr.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>