Remove CHARSETNR_SIZE from generated headers

and prefix it with MYSQL2_ to match existing definitions.

Author: felixbuenemann

ext/mysql2/mysql_enc_to_ruby.h

@@ -255,5 +255,3 @@ static const char *mysql2_mysql_enc_to_rb[] = {
   NULL,
   "UTF-8"
 };
-
-#define CHARSETNR_SIZE (sizeof(mysql2_mysql_enc_to_rb)/sizeof(mysql2_mysql_enc_to_rb[0]))

ext/mysql2/result.c

@@ -1,6 +1,7 @@
 #include <mysql2_ext.h>
 
 #include "mysql_enc_to_ruby.h"
+#define MYSQL2_CHARSETNR_SIZE (sizeof(mysql2_mysql_enc_to_rb)/sizeof(mysql2_mysql_enc_to_rb[0]))
 
 static rb_encoding *binaryEncoding;
 
@@ -179,7 +180,7 @@ static VALUE mysql2_set_field_string_encoding(VALUE val, MYSQL_FIELD field, rb_e
     const char *enc_name;
     int enc_index;
 
-    enc_name = (field.charsetnr-1 < CHARSETNR_SIZE) ? mysql2_mysql_enc_to_rb[field.charsetnr-1] : NULL;
+    enc_name = (field.charsetnr-1 < MYSQL2_CHARSETNR_SIZE) ? mysql2_mysql_enc_to_rb[field.charsetnr-1] : NULL;
 
     if (enc_name != NULL) {
       /* use the field encoding we were able to match */