Revert "Remove an unnecessary wx translation underscore macro from PHackSettings."

This reverts commit 110f603cb68ef7eadd0704c8419ec0a06737af98.
Fix a crash that got recently introduced.

When CFileSystemGCWii::GetFileName can't find a valid filename it would return nullptr.
nullptr as a std::string throws an assert within the std lib.
So return an empty string and check if it is empty or not
Merge pull request #203 from Sonicadvance1/fix-crash

Fix a crash that got recently introduced.
Merge pull request #201 from Sonicadvance1/Revert-PR179

Revert "Remove an unnecessary wx translation underscore macro from PHackSettings."
FPURoundMode: use fesetround() instead of asm