Move flymake test data to more standard location

* test/automated/flymake-tests.el (flymake-tests-data-directory):
Change from flymake/warnpred to more standard data/flymake.

* .gitignore: Update for relocated flymake test data.
Disable gcc color in test/automated/data/flymake/Makefile

* test/automated/data/flymake/Makefile (check-syntax):
Prevent colorized gcc output from confusing flymake.