Unify DATA only symbols imported from msvcr*
Add hypot and atan2 to libmingwex for x86 and x64.
Mark some math functions in 64-bit as DATA, and remove DATA for asin, acos, atan
Replace acos/asin/atan DATA attribute, as we don't provide own implementation for them right now.
We don't have tan implementation, therefore we need stub-code into msvcrt ...