vrt: Bind FORMAT_MESSAGE_FROM_HMODULE.

Author: bhelyer

rt/src/core/c/windows/windows.volt

@@ -148,6 +148,7 @@ fn GetLastError() DWORD;
 enum FORMAT_MESSAGE_ALLOCATE_BUFFER = 0x00000100;
 enum FORMAT_MESSAGE_FROM_SYSTEM     = 0x00001000;
 enum FORMAT_MESSAGE_IGNORE_INSERTS  = 0x00000200;
+enum FORMAT_MESSAGE_FROM_HMODULE    = 0x00000800;
 
 fn FormatMessageA(DWORD, LPCVOID, DWORD, DWORD, LPCSTR, DWORD, va_list*) DWORD;
 fn FormatMessageW(DWORD, LPCVOID, DWORD, DWORD, LPCWSTR, DWORD, va_list*) DWORD;