WL#8077 Extend mysql_real_escape() to be aware of the string type it's escaping for.

mysql_real_escape_string() function was found insecure when sql_mode was set to
NO_BACKSLASH_ESCAPES. mysql_real_escape_string() function reports error when sql_mode
is set to NO_BACKSLASH_ESCAPES.

Newly introduced API function mysql_real_escape_string_quote() should be used instead.
Additional char type parameter allows to specify, which character should be doubled.
Doubled character is a quote character of the identifier or a string within a SQL query.

tests/mysql_client_test.c
  Fixed test_bug21246 test - buffer overflow.

Author: maras007

tests/mysql_client_test.c

@@ -14100,7 +14100,7 @@ static void test_bug10214()
 static void test_bug21246()
 {
   int   len;
-  char  out[10];
+  char  out[11];
 
   myheader("test_bug21246");