This is no-op for usual GCC targets, because we don't pass any string to CreateSemaphore anyway. However this trivial change will help mingw-w64's efforts to support WinRT, where only unicode variant is available.
libgcc/Changelog:
config/i386/gthr-win32.c: CreateSemaphoreW instead of CreateSemaphoreA.
config/i386/gthr-win32.h: Likewise.
