gsm_rlcmac: Use 'struct bitvec' instead of 'bitvec'

The later is only accepted when compiling as c++.

Change-Id: Ib5004643d4eff3bc9d11b66ddaf262f1c0d2aef6
diff --git a/tests/rlcmac/RLCMACTest.cpp b/tests/rlcmac/RLCMACTest.cpp
index 200cac8..a21c22d 100644
--- a/tests/rlcmac/RLCMACTest.cpp
+++ b/tests/rlcmac/RLCMACTest.cpp
@@ -215,7 +215,7 @@
 	msgb_free(m);
 }
 
-int encode_gsm_ra_cap(bitvec * vector, MS_Radio_Access_capability_t * data);
+int encode_gsm_ra_cap(struct bitvec *vector, MS_Radio_Access_capability_t * data);
 
 void testRAcap(void *test_ctx)
 {