h5_test/tst_h_rd_cmp can be combined with tst_h_wrt_cmp to eliminate dependency

[edhartnett]

The test file h5_test/tst_h_rd_cmp.c used the output from tst_h_wrt_cmp.c. This creates a dependency between the tests. These are short code files, so no need to have this test in two code files. The read test simply reads what the write test produces.

I will combine these tests and eliminate tst_h_rd_cmp.

[edhartnett]

The reason this was not breaking any parallel builds is because tst_h_rd_cmp was not being run. In PR #680 I move the test code from tst_h_rd_cmp.c to tst_h_wrt_cmp.c, and eliminate tst_h_rd_cmp.c.