tools, bpftool: Poison and replace kernel integer typedefs

Replace the use of kernel-only integer typedefs (u8, u32, etc.) by their
user space counterpart (__u8, __u32, etc.).

Similarly to what libbpf does, poison the typedefs to avoid introducing
them again in the future.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200511161536.29853-2-quentin@isovalent.com

tools/bpf/bpftool/main.h

@@ -18,6 +18,9 @@
 
 #include "json_writer.h"
 
+/* Make sure we do not use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
 #define ptr_to_u64(ptr)	((__u64)(unsigned long)(ptr))
 
 #define NEXT_ARG()	({ argc--; argv++; if (argc < 0) usage(); })