Remove faulty resource mark from print_symbol_on().

If a stringStream is passed to Symbol::print_symbol_on(),
assertion "stringStream is re-allocated with a different ResourceMark." can fire in stringStream::write(const char* s, size_t len).

This can be verified by running TestLogTouchedMethods.java after adding this patch to the VM:

--- a/src/share/vm/runtime/java.cpp Wed Jan 13 11:33:21 2016 +0100
+++ b/src/share/vm/runtime/java.cpp Wed Feb 10 08:56:14 2016 +0100
@@ -340,7 +340,10 @@
   }

   if (LogTouchedMethods && PrintTouchedMethodsAtExit) {
- Method::print_touched_methods(tty);
+ ResourceMark rm;
+ stringStream st(16);
+ Method::print_touched_methods(&st);
+ tty->print("%s", st.as_string());
   }

   if (PrintBiasedLockingStatistics) {