This commit adds tests for the limits added in a previous commit. The
limits are defined in decimal in stdint.h and as hexadecimal in the
tests (e.g. 0x7f = 127 or 0x80 = -128). Hopefully it catches some of the
most egregious mistakes.

As we rely on the compiler to provide __SIZEOF_LONG__, we also test
whether it is defined.
Signed-off-by: Vincent Dagonneau <v@vda.io>
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>