tools/resolve_btfids: Fix build error with older host toolchains

commit 41462c6 upstream.

Older libelf.h and glibc elf.h might not yet define the ELF compression
types.

Checking and defining SHF_COMPRESSED fix the build error when compiling
with older toolchains. Also, the tool resolve_btfids is compiled with host
toolchain. The host toolchain is more likely to be older than the cross
compile toolchain.

Fixes: 51f6463 ("tools/resolve_btfids: Fix sections with wrong alignment")
Signed-off-by: Kun-Chuan Hsieh <jetswayss@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20210224052752.5284-1-jetswayss@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/bpf/resolve_btfids/main.c

@@ -258,6 +258,11 @@ static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
 	return btf_id__add(root, id, false);
 }
 
+/* Older libelf.h and glibc elf.h might not yet define the ELF compression types. */
+#ifndef SHF_COMPRESSED
+#define SHF_COMPRESSED (1 << 11) /* Section with compressed data. */
+#endif
+
 /*
  * The data of compressed section should be aligned to 4
  * (for 32bit) or 8 (for 64 bit) bytes. The binutils ld