Fixed compiler warnings and warnings from build.tags

Other things
- Ensure that ut_d() is set to EXPR if ut_ad() is DEBUG_ASSERT()
  If not, we will get a crash in purge_sys_t::~purge_sys_t() as
  this ut_ad() code expect's that the ut_d() codes has been executed

client/mysqlcheck.c

@@ -19,6 +19,8 @@
 /* By Jani Tolonen, 2001-04-20, MySQL Development Team */
 
 #define CHECK_VERSION "2.7.4-MariaDB"
+/* Avoid warnings from %'s format */
+#define USING_MARIADB_SNPRINTF_EXTENSIONS
 
 #include "client_priv.h"
 #include <m_ctype.h>