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/extras/libmemif/examples/icmp_responder-epoll/main.c b/extras/libmemif/examples/icmp_responder-epoll/main.c
index 02414fa..ecc05a4 100644
--- a/extras/libmemif/examples/icmp_responder-epoll/main.c
+++ b/extras/libmemif/examples/icmp_responder-epoll/main.c
@@ -372,7 +372,6 @@
 
   int err = MEMIF_ERR_SUCCESS, ret_val;
   uint16_t rx = 0, tx = 0;
-  uint16_t fb = 0;
   int i = 0;			/* rx buffer iterator */
   int j = 0;			/* tx bufferiterator */
 
@@ -457,10 +456,8 @@
 
   int err = MEMIF_ERR_SUCCESS, ret_val;
   uint16_t rx = 0, tx = 0;
-  uint16_t fb;
   int i;			/* rx buffer iterator */
   int j;			/* tx bufferiterator */
-  int prev_i;			/* first allocated rx buffer */
 
   /* loop while there are packets in shm */
   do
@@ -475,7 +472,7 @@
 	  goto error;
 	}
 
-      prev_i = i = 0;
+      i = 0;
 
       /* loop while there are RX buffers to be processed */
       while (rx)
@@ -522,7 +519,6 @@
 	  if (err != MEMIF_ERR_SUCCESS)
 	    INFO ("memif_buffer_free: %s", memif_strerror (err));
 	  rx -= j;
-	  prev_i = i;
 
 	  DBG ("freed %d buffers. %u/%u alloc/free buffers",
 	       fb, rx, MAX_MEMIF_BUFS - rx);
@@ -570,8 +566,6 @@
   int err = MEMIF_ERR_SUCCESS, ret_val;
   int i;
   uint16_t rx, tx;
-  uint16_t fb;
-  uint16_t pck_seq;
 
   do
     {
@@ -639,7 +633,6 @@
 
   /* setting memif connection arguments */
   memif_conn_args_t args;
-  int fd = -1;
   memset (&args, 0, sizeof (args));
   args.is_master = mode;
   args.log2_ring_size = 11;
@@ -1106,7 +1099,6 @@
 int
 user_input_handler ()
 {
-  int i;
   char *in = (char *) malloc (256);
   char *ui = fgets (in, 256, stdin);
   char *end;
@@ -1223,9 +1215,8 @@
 int
 poll_event (int timeout)
 {
-  struct epoll_event evt, *e;
+  struct epoll_event evt;
   int app_err = 0, memif_err = 0, en = 0;
-  int tmp, nfd;
   uint32_t events = 0;
   struct timespec start, end;
   memset (&evt, 0, sizeof (evt));