Make possible to use clang on Windows (clang-cl)

-DWITH_ASAN can be used as well now, on x64

Fix many clang-cl warnings.

client/mysql.cc

@@ -1709,13 +1709,12 @@ static struct my_option my_long_options[] =
 
 static void usage(int version)
 {
+#ifdef HAVE_READLINE
 #if defined(USE_LIBEDIT_INTERFACE)
   const char* readline= "";
 #else
   const char* readline= "readline";
 #endif
-
-#ifdef HAVE_READLINE
   printf("%s  Ver %s Distrib %s, for %s (%s) using %s %s\n",
 	 my_progname, VER, MYSQL_SERVER_VERSION, SYSTEM_TYPE, MACHINE_TYPE,
          readline, rl_library_version);