Add testcase for stub-method reading in stabs.

Add testcase for stub-method reading in stabs.

This patch is based on the testcase provided here:
https://sourceware.org/ml/gdb-patches/2015-02/msg00181.html

I've verified that it catches the internal error discovered here:
https://sourceware.org/ml/gdb-patches/2015-02/msg00139.html

gdb/testsuite/ChangeLog:

	* lib/gdb.exp (clean_restart): Return result of gdb_load.
	* gdb.pascal/stub-method.exp: New file.
	* gdb.pascal/stub-method.pas: New file.