libbpf: add common min/max macro to libbpf_internal.h

Multiple files in libbpf redefine their own definitions for min/max.
Let's define them in libbpf_internal.h and use those everywhere.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

src/btf.c

@@ -16,9 +16,6 @@
 #include "libbpf_internal.h"
 #include "hashmap.h"
 
-#define max(a, b) ((a) > (b) ? (a) : (b))
-#define min(a, b) ((a) < (b) ? (a) : (b))
-
 #define BTF_MAX_NR_TYPES 0x7fffffff
 #define BTF_MAX_STR_OFFSET 0x7fffffff