Fixed some compiler warnings

configure.in:
  Added comment
mysql-test/suite/innodb_plugin/t/innodb_bug56680.test:
  Disable test when run with valgrind as we get errors from buf_buddy_relocate() on work for this test.
  (Should probably be investigated as this may be an issue in xtradb, but probably harmless)
  Work is an amd-64 running openSUSE 1.11 and valgrind 3.4.1
mysys/charset.c:
  Remove static function if not used (to remove compiler warning)
storage/xtradb/srv/srv0srv.c:
  Added casts to get rid of compiler warnings

configure.in

@@ -123,6 +123,7 @@ then
 fi
 
 # Whether the maintainer mode should be enabled.
+# Note that this uses $with_debug and $with_valgrind
 MY_MAINTAINER_MODE
 
 # Canonicalize the configuration name.

mysql-test/suite/innodb_plugin/t/innodb_bug56680.test

@@ -2,6 +2,7 @@
 # Bug #56680 InnoDB may return wrong results from a case-insensitive index
 #
 -- source include/have_innodb_plugin.inc
+-- source include/not_valgrind.inc
 
 -- disable_query_log
 SET @tx_isolation_orig = @@tx_isolation;

mysys/charset.c

@@ -202,6 +202,7 @@ static my_bool simple_cs_is_full(CHARSET_INFO *cs)
 }
 
 
+#if defined(HAVE_UCA_COLLATIONS) && (defined(HAVE_CHARSET_ucs2) || defined(HAVE_CHARSET_utf8))
 static void
 copy_uca_collation(CHARSET_INFO *to, CHARSET_INFO *from)
 {
@@ -215,6 +216,7 @@ copy_uca_collation(CHARSET_INFO *to, CHARSET_INFO *from)
   to->state|= MY_CS_AVAILABLE | MY_CS_LOADED |
               MY_CS_STRNXFRM  | MY_CS_UNICODE;
 }
+#endif
 
 
 static int add_collation(CHARSET_INFO *cs)

storage/xtradb/srv/srv0srv.c

@@ -1125,7 +1125,7 @@ retry:
 			enter_innodb_with_tickets(trx);
 			return;
 		}
-		os_atomic_increment_lint(&srv_conc_n_threads, -1);
+		(void) os_atomic_increment_lint(&srv_conc_n_threads, -1);
 	}
 	if (!has_yielded)
 	{
@@ -1155,7 +1155,7 @@ retry:
 static void
 srv_conc_exit_innodb_timer_based(trx_t* trx)
 {
-	os_atomic_increment_lint(&srv_conc_n_threads, -1);
+        (void) os_atomic_increment_lint(&srv_conc_n_threads, -1);
 	trx->declared_to_be_inside_innodb = FALSE;
 	trx->n_tickets_to_enter_innodb = 0;
 	return;
@@ -1362,7 +1362,7 @@ srv_conc_force_enter_innodb(
 	ut_ad(srv_conc_n_threads >= 0);
 #ifdef HAVE_ATOMIC_BUILTINS
 	if (srv_thread_concurrency_timer_based) {
-		os_atomic_increment_lint(&srv_conc_n_threads, 1);
+                (void) os_atomic_increment_lint(&srv_conc_n_threads, 1);
 		trx->declared_to_be_inside_innodb = TRUE;
 		trx->n_tickets_to_enter_innodb = 1;
 		return;