create-for-stream often fails whilst running under valgrind due to the
postscript output containing a CreationDate with seconds resolution,
hence the visibility of the resource leaks during failure.
Without this, any tests that were using cairo_test_init rather than
cairo_test would end up leaking a FILE* for the log file. So this
keeps valgrind much more happy with the test suite.
- Remove cairo_test_expect_failure. cairo-test.c now checks
env var CAIRO_XFAIL_TESTS to see if the running test is
expected to fail. The reason for expected failure is
appended to the test description.
- Test description is written out.
- Failed/crashed tests also write a line out to stderr (in red),
so one can now redirect stdout to /dev/null to only see failures.
- cairo_test() has been changed to not take the draw function
anymore, instead, draw function is now part of the test struct.
- "make check" doesn't allow limiting backends to test using env
var anymore. To limit backends to test, one should use the
TARGETS variable on the make command line.
- "make check-valgrind" now writes its log to valgrind-log instead
of valgrind.log, to not interfere with test log file processing.
