Fix test cases to work for i386.
    
    gold/
    	PR gold/21039
    	* testsuite/script_test_13.sh: Adjust patterns to work for i386.
    	* testsuite/script_test_15a.sh: Likewise.
    	* testsuite/script_test_15b.sh: Likewise.
    	* testsuite/script_test_15c.sh: Likewise.