ctest_build: ignore ANSI color
Ignore ANSI color when scraping logs for errors and warnings.
The motivation behind this change was a a bug that occurred when using Clang's -fcolor-diagnostics
flag without CTest launchers. In this situation, the inserted color code would cause the following "error exception" regex to no longer match.
https://gitlab.kitware.com/cmake/cmake/blob/master/Source/CTest/cmCTestBuildHandler.cxx#L86
The result was that the warning was being detected as an error by CTest.
Edited by Zack Galbreath