In 7f530cc we taught CTest to pass extra information to CDash at submit
time. This extra info is used by CDash to initialize a buildid.
`ctest_submit(FILES)` can be used to send specific files to CDash.
These files are not necessarily associated with the build currently
being performed. For this reason, we modify the behavior of ctest_submit()
to only specify this extra info when we are submitting files from the
current build's Testing directory.
Hide any headers specified by `ctest_submit(HTTPHEADER ...)` unless ctest
is run with --debug. This option is used to present bearer tokens to CDash.
We do not want to inadvertently expose this secret data in the console
output log.
Allow CTest script writers to specify additional HTTP headers to be sent
to CDash during submission.
The motivating case for this feature is a corresponding change in CDash.
This will allow projects to refuse submissions from any site not bearing
a valid authentication token.
A more-specific error message is always displayed earlier in the
output if any real error occurred. This final summary message
is distracting to readers searching through the output for the
word "error". Simply drop it.