This patch adds three end-to-end test case for incremental update.

(I removed the Makefile.in diffs from the patch.)

-cary


	* testsuite/Makefile.am: Add incremental_test_2, incremental_test_3,
	incremental_test_4.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/two_file_test_1_v1.cc: New test source file.
	* testsuite/two_file_test_1b_v1.cc: New test source file.
	* testsuite/two_file_test_2_v1.cc: New test source file.