Remove dependency on eglplatform.h header

Fixes #636.

docs/compile.dox

@@ -281,6 +281,12 @@ available:
  - `_GLFW_USE_RETINA` to have windows use the full resolution of Retina displays
    (recommended)
 
+If you are using the EGL context creation API, the following options are
+available:
+
+ - `_GLFW_USE_EGLPLATFORM_H` to use `EGL/eglplatform.h` for native handle
+   definitions (fallback)
+
 @note None of the @ref build_macros may be defined during the compilation of
 GLFW.  If you define any of these in your build files, make sure they are not
 applied to the GLFW sources.

src/egl_context.h

@@ -39,7 +39,27 @@
  #define _glfw_dlsym(handle, name) dlsym(handle, name)
 #endif
 
-#include <EGL/eglplatform.h>
+#if defined(_GLFW_USE_EGLPLATFORM_H)
+ #include <EGL/eglplatform.h>
+#elif defined(_GLFW_WIN32)
+ #define EGLAPIENTRY __stdcall
+typedef HDC EGLNativeDisplayType;
+typedef HWND EGLNativeWindowType;
+#elif defined(_GLFW_X11)
+ #define EGLAPIENTRY
+typedef Display* EGLNativeDisplayType;
+typedef Window EGLNativeWindowType;
+#elif defined(_GLFW_WAYLAND)
+ #define EGLAPIENTRY
+typedef struct wl_display* EGLNativeDisplayType;
+typedef struct wl_egl_window* EGLNativeWindowType;
+#elif defined(_GLFW_MIR)
+ #define EGLAPIENTRY
+typedef MirEGLNativeDisplayType EGLNativeDisplayType;
+typedef MirEGLNativeWindowType EGLNativeWindowType;
+#else
+ #error "No supported EGL platform selected"
+#endif
 
 #define EGL_SUCCESS	0x3000
 #define EGL_NOT_INITIALIZED	0x3001
@@ -94,6 +114,7 @@
 #define EGL_NO_DISPLAY ((EGLDisplay) 0)
 #define EGL_NO_CONTEXT ((EGLContext) 0)
 
+typedef int EGLint;
 typedef unsigned int EGLBoolean;
 typedef unsigned int EGLenum;
 typedef void* EGLConfig;