prevent warnings from creeping back in, we now have the ability to break the
build when new warnings appear.
-This is only available for systems with gcc 4.2 or later, and is disabled
-unless the --enable-checking option is supplied to configure. Because we
-can't remove all of the warnings, we permit file by file (and warning by
-warning) disabling of specific warnings. The --enable-checking=all prevents
+This is only available for systems with gcc 4.2 or later or clang 3.2 or
+later, and is disabled unless the --enable-checking option is supplied to
+configure. Because we can't remove all of the warnings, we permit file by
+file (and warning by warning) disabling of specific warnings. The
+--enable-checking=all option prevents
this, and errors for any file containing a warning.
Disabling warnings