Free the temporary vector

vec_add1() seems to be allocating memory which we do not free. Correct
that.

Change-Id: I25dca1871121cdd11a218ff2289a3c51b42e843b
Signed-off-by: Robert Varga <nite@hq.sk>
diff --git a/vpp-japi/japi/vppjni.c b/vpp-japi/japi/vppjni.c
index f7047bb..83090cf 100644
--- a/vpp-japi/japi/vppjni.c
+++ b/vpp-japi/japi/vppjni.c
@@ -901,6 +901,8 @@
 
     (*env)->SetIntArrayRegion(env, bdidArray, 0, vec_len(buf), (int*)buf);
 
+    vec_free(buf);
+
     return bdidArray;
 }