bpftool: Allow building statically

Sometime it can be useful to haul around a statically built version of
bpftool. Simply add support for passing STATIC=1 while building to build
the tool statically.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>

Author: lorddoskias

tools/bpf/bpftool/Makefile

@@ -13,6 +13,10 @@ else
   Q = @
 endif
 
+ifeq ($(STATIC),1)
+	CFLAGS += --static
+endif
+
 BPF_DIR = $(srctree)/tools/lib/bpf
 
 ifneq ($(OUTPUT),)