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/engine/engine.h

@@ -485,6 +485,9 @@ class DivEngine {
     // returns the minimum VGM version which may carry the specified system, or 0 if none.
     int minVGMVersion(DivSystem which);
 
+    // determine and setup config dir
+    void initConfDir();
+
     // save config
     bool saveConf();