Haiku support (#596)

* Don't apply Wayland videodriver workaround on Haiku

* dirent.d_type-less type detecting in IGFD

The Dumb Way(tm). `stat`'s `st_mode` should be nicer?

* CMake check for dirent.d_type, stat-based fallback

* Move config dir setup to separate function

Nicer to work with than macro kerfuffle.

* Default sysFileDialog to off on Haiku

* Logging stuff

* Honour CMAKE_INSTALL_BINDIR

* Use find_directory on Haiku

Includes forgotten configPath line when home==NULL.

* Address PR review notes

src/main.cpp

@@ -295,7 +295,7 @@ int main(int argc, char** argv) {
     logE("CoInitializeEx failed!");
   }
 #endif
-#if !(defined(__APPLE__) || defined(_WIN32) || defined(ANDROID))
+#if !(defined(__APPLE__) || defined(_WIN32) || defined(ANDROID) || defined(__HAIKU__))
   // workaround for Wayland HiDPI issue
   if (getenv("SDL_VIDEODRIVER")==NULL) {
     setenv("SDL_VIDEODRIVER","x11",1);