build: add -Wall and -fno-common, fix reported issues

Type: refactor
Change-Id: I8489ccd54411c2aa9355439c5641dc31012c64a2
Signed-off-by: Benoît Ganne <bganne@cisco.com>
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vcl/vcl_test.h b/src/vcl/vcl_test.h
index a5a8ad1..ab05f7a 100644
--- a/src/vcl/vcl_test.h
+++ b/src/vcl/vcl_test.h
@@ -404,7 +404,7 @@
 vcl_test_read (int fd, uint8_t * buf, uint32_t nbytes,
 	       vcl_test_stats_t * stats)
 {
-  int rx_bytes, errno_val;
+  int rx_bytes;
 
   do
     {
@@ -443,7 +443,7 @@
 static inline int
 vcl_test_read_ds (int fd, vppcom_data_segments_t ds, vcl_test_stats_t * stats)
 {
-  int rx_bytes, errno_val;
+  int rx_bytes;
 
   do
     {