libbpf: Fix map creation flags sanitization

As BPF_F_MMAPABLE flag is now conditionnaly set (by map_is_mmapable),
it should not be toggled but disabled if not supported by kernel.

Fixes: 4fcac46c ("libbpf: only add BPF_F_MMAPABLE flag for data maps with global vars")
Signed-off-by: Ludovic L'Hours <ludovic.lhours@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230108182018.24433-1-ludovic.lhours@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/lib/bpf/libbpf.c

@@ -7355,7 +7355,7 @@ static int bpf_object__sanitize_maps(struct bpf_object *obj)
 		if (!bpf_map__is_internal(m))
 			continue;
 		if (!kernel_supports(obj, FEAT_ARRAY_MMAP))
-			m->def.map_flags ^= BPF_F_MMAPABLE;
+			m->def.map_flags &= ~BPF_F_MMAPABLE;
 	}
 
 	return 0;