This commit adds some of the missing integer types to stdint.h and adds
limit macros (e.g. INTN_{MIN,MAX}).

The reference used for adding these types is
https://pubs.opengroup.org/onlinepubs/009695399/basedefs/stdint.h.html.

We rely on the compiler-defined __LONG_MAX__ to get the right limits for
size_t, intptr_t, uintptr_t and ptrdiff_t. This compiler constant seem
to have been defined at least since GCC 4.1.2 and clang
3.0.0 on x86_64. It is also defined on ARM (32&64), mips and RISC-V.

Note that the maximum size of size_t is implementation-defined (>65535),
in this case I chose to go with unsigned long on all platforms since
unsigned long == unsigned int on all the platforms we care about. Note
that the kernel uses either unsigned int or unsigned long in
linux/include/uapi/asm-generic/posix_types.h. These should be equivalent
for the plaforms we are targeting.

Also note that the 'fast*' flavor of the types have been chosen to be
always 1 byte for '*fast8*' and always long (a.k.a. intptr_t/uintptr_t) for
the other variants. I have never seen the 'fast*' types in use in the wild
but that seems to be what glibc does.
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>