[compiler-rt] [profile] Fix building for MinGW after d889d1ef

This commit added use of a Windows API in InstrProfilingPort.h.
When _MSC_VER is defined (for MSVC), windows.h is already included
earlier in the same header (for atomics), but MinGW, the gcc
atomics builtins are used instead. Therefore explicitly include
windows.h here, where the API is used.