minimingw no longer works with current hxcpp

[tobil4sk]

I'm not sure if this is still intended for use, however, it is still recommended in the Haxe manual.

Firstly, this library only works if HXCPP_M32 is set, and compiling with HXCPP_M64 causes compiler errors, see: HaxeFoundation/hxcpp#1031

When HXCPP_M32 is set, compilation still fails due to missing parts of the Windows API in minimingw:

Error: D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:628:2: error: 'CONDITION_VARIABLE' does not name a type
  CONDITION_VARIABLE cond;
  ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp: In constructor 'hxCondition::hxCondition()':
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:641:31: error: 'cond' was not declared in this scope
  InitializeConditionVariable(&cond);
                               ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:641:35: error: 'InitializeConditionVariable' was not declared in this scope
  InitializeConditionVariable(&cond);
                                   ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp: In member function 'void hxCondition::Wait()':
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:711:30: error: 'cond' was not declared in this scope
    SleepConditionVariableCS(&cond,&cs,INFINITE);
                              ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:711:47: error: 'SleepConditionVariableCS' was not declared in this scope
    SleepConditionVariableCS(&cond,&cs,INFINITE);
                                               ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp: In member function 'bool hxCondition::TimedWait(double)':
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:721:43: error: 'cond' was not declared in this scope
    return (bool)SleepConditionVariableCS(&cond, &cs, (DWORD)((FLOAT)timeout * 1000.0));
                                           ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:721:86: error: 'SleepConditionVariableCS' was not declared in this scope
    return (bool)SleepConditionVariableCS(&cond, &cs, (DWORD)((FLOAT)timeout * 1000.0));
                                                                                      ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp: In member function 'void hxCondition::Signal()':
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:744:27: error: 'cond' was not declared in this scope
    WakeConditionVariable(&cond);
                           ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:744:31: error: 'WakeConditionVariable' was not declared in this scope
    WakeConditionVariable(&cond);
                               ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp: In member function 'void hxCondition::Broadcast()':
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:753:30: error: 'cond' was not declared in this scope
    WakeAllConditionVariable(&cond);
                              ^
D:/Dev/Haxe/hxcpp/src/hx/Thread.cpp:753:34: error: 'WakeAllConditionVariable' was not declared in this scope
    WakeAllConditionVariable(&cond);
                                  ^
Error: Build failed

Newer mingw does not have this issue, so it looks like minimingw is just out of date.