Tags that influence translation

<preprocess_first>: Specifies if the build fails because of errors in cov-emit's preprocessing. If this is specified, cov-build tries to preprocess each file with the native compiler before sending it to cov-emit. This tag does not take a value.
The command to run to preprocess a file is configured by the <preprocess_> options given next. It is constructed based on the command line used to actually compile the file.
<cygwin>: Indicates that the given compiler supports Cygwin file processing.