string.c: constify

* string.c (tr_find): constify argument table.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43699 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

string.c

@@ -5710,7 +5710,7 @@ tr_setup_table(VALUE str, char stable[TR_TABLE_SIZE], int first,
 
 
 static int
-tr_find(unsigned int c, char table[TR_TABLE_SIZE], VALUE del, VALUE nodel)
+tr_find(unsigned int c, const char table[TR_TABLE_SIZE], VALUE del, VALUE nodel)
 {
     if (c < 256) {
 	return table[c] != 0;