winpthreads: simplify the USE_VEH_FOR_MSC_SETTHREADNAME check

When compiling with other compilers than MSVC, we always use the code
relying on USE_VEH_FOR_MSC_SETTHREADNAME.

The __try/__except check code is not modified as it relies on internal MSVC
dialect. With MSVC either USE_VEH_FOR_MSC_SETTHREADNAME was set but that code
wasn't use anyway (unchanged) or it wasn't set and we use the code (unchanged).
Without MSVC we always define USE_VEH_FOR_MSC_SETTHREADNAME so the other
variant of the code is used (unchanged).

Signed-off-by: Liu Hao <lh_mouse@126.com>
1 file changed