Coverity fixes round 6
The tests have never run successfully and we do have successful builds of mingw-w64, so remove these CI builds which do not add value.
Curl by default does not report errors by setting the error code.
As the upload can fail through several conditions (e.g. the rate
limit, leading to unauthorized access) we should indicate this
information in Travis CI.
To improve upon the behavior, use `--write-out=%{http_code}` to
write out the HTTP code in addition to the received body and
return an error if the code does not equal 201.
We were missing this test on Windows, which meant we didn't notice that we never fixed the single authentication attempt it tries, nor its wrong return code. Enable this for the unix platforms as well over HTTP. We previously were doing it locally but disabled it on OS X due to issues with its sshd not accepting password authentication.
We commonly have to check if a git_buf has been allocated correctly or if we ran out of memory. Introduce a new macro similar to `GITERR_CHECK_ALLOC` which checks if we ran OOM and if so returns an error. Provide a `#nodef` for Coverity to mark the error case as an abort path.
Coverity does not comprehend the connection between a vector's size and the contents pointer, that is that the vector's pointer is non-NULL when its size is positive. As the vector code should be reasonably well tested and users are expected to not manually modify a vector's contents it seems save to assume that the macros will never dereference a NULL pointer. Fix Coverity warnings by overriding the foreach macros with macros that explicitly aborting when (v)->contents is NULL.
When checking if a string is prefixed by a drive letter (e.g. "C:") we verify this by inspecting the first and second character of the string. Coverity thinks this is a defect as we do not check the string's length first, but in fact we only check the second character if the first character is part of the alphabet, that is it cannot be '\0'. Fix this by overriding the macro and explicitly checking the string's length.
Add nodefs for macros that abort the current flow due to errors. This includes macros that trigger on integer overflows and for the version check macro. This aids Coverity as we point out that these paths will cause a fatal error.
When posting our instrumented build results to Coverity we have to include sensitive information, in particular our authorization token. Currently we use an unencrypted channel to post this information, leading to the token being transferred in plain. Fix this by using a secured connection instead.