eval_error.c: should not escapce newline and tab

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66917 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

eval_error.c

@@ -87,6 +87,9 @@ write_warnq(VALUE out, VALUE str, const char *ptr, long len)
         const long olen = len;
         for (; len > 0; --len, ++ptr) {
             unsigned char c = *ptr;
+            switch (c) {
+              case '\n': case '\t': continue;
+            }
             if (rb_iscntrl(c)) {
                 char buf[5];
                 const char *cc = 0;