tc: {f,m}_bpf: allow to retrieve uds path from env

Allow to retrieve uds path from the environment, facilitates
also dealing with export a bit.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/tc/tc_bpf.h b/tc/tc_bpf.h
index 5a697e5..2ad8812 100644
--- a/tc/tc_bpf.h
+++ b/tc/tc_bpf.h
@@ -25,6 +25,8 @@
 #include "utils.h"
 #include "bpf_scm.h"
 
+#define BPF_ENV_UDS	"TC_BPF_UDS"
+
 int bpf_parse_string(char *arg, bool from_file, __u16 *bpf_len,
 		     char **bpf_string, bool *need_release,
 		     const char separator);