Call `get_errc_messages` only if `LLVM_INCLUDE_TESTS` was set.
Reviewed By: zero9178, abhina.sreeskantharajan, jhenderson
Differential Revision: https://reviews.llvm.org/D98861
If for some reason the test program does not exit normally it'd currently lead to a false positive and it's stdout output being assigned to the output variable.
Instead, check the test program exited normally before assigning the process output to the out variable.
Follow up on rGaf2796c76d2ff4b73165ed47959afd35a769beee
Fixes an issue discovered post commit in https://reviews.llvm.org/D98278
Visual Studios implementation of the C++ Standard Library does not use strerror to produce a message for std::error_code unlike other standard libraries such as libstdc++ or libc++ that might be used.
This patch adds a cmake script that through running a C++ program gets the error messages for the POSIX error codes and passes them onto lit through an optional config parameter.
If the config parameter is not set, or getting the messages failed, due to say a cross compiling configuration without an emulator, it will fall back to using pythons strerror functions.
Differential Revision: https://reviews.llvm.org/D98278
John Brawn