Platform: Ensure classes match their header filename

Also drop some unused files.

Renamed:
- `platform/iphone/sem_iphone.h` -> `semaphore_iphone.h`
  (same for `osx`)
- `platform/uwp/gl_context_egl.h` -> `context_egl_uwp.h`
- in `platform/windows`: `context_gl_win.h`, `crash_handler_win.h`,
  `godot_win.cpp`, `joypad.h` and `key_mapping_win.h` all renamed to
  use `windows`. Some classes renamed accordingly too.
- `EditorExportAndroid` and `EditorExportUWP` renamed to
  `EditorExportPlatformAndroid` and `EditorExportPlatformUWP`
- `power_android` and `power_osx` renamed to `PowerAndroid` and
  `PowerOSX`
- `OSUWP` renamed to `OS_UWP`

Dropped:
- `platform/windows/ctxgl_procaddr.h`

platform/osx/semaphore_osx.cpp

@@ -0,0 +1,107 @@
+/*************************************************************************/
+/*  semaphore_osx.cpp                                                    */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "semaphore_osx.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+
+void cgsem_init(cgsem_t *cgsem) {
+	int flags, fd, i;
+
+	pipe(cgsem->pipefd);
+
+	/* Make the pipes FD_CLOEXEC to allow them to close should we call
+	 * execv on restart. */
+	for (i = 0; i < 2; i++) {
+		fd = cgsem->pipefd[i];
+		flags = fcntl(fd, F_GETFD, 0);
+		flags |= FD_CLOEXEC;
+		fcntl(fd, F_SETFD, flags);
+	}
+}
+
+void cgsem_post(cgsem_t *cgsem) {
+	const char buf = 1;
+
+	write(cgsem->pipefd[1], &buf, 1);
+}
+
+void cgsem_wait(cgsem_t *cgsem) {
+	char buf;
+
+	read(cgsem->pipefd[0], &buf, 1);
+}
+
+void cgsem_destroy(cgsem_t *cgsem) {
+	close(cgsem->pipefd[1]);
+	close(cgsem->pipefd[0]);
+}
+
+#include "core/os/memory.h"
+
+#include <errno.h>
+
+Error SemaphoreOSX::wait() {
+
+	cgsem_wait(&sem);
+	return OK;
+}
+
+Error SemaphoreOSX::post() {
+
+	cgsem_post(&sem);
+
+	return OK;
+}
+int SemaphoreOSX::get() const {
+
+	return 0;
+}
+
+Semaphore *SemaphoreOSX::create_semaphore_osx() {
+
+	return memnew(SemaphoreOSX);
+}
+
+void SemaphoreOSX::make_default() {
+
+	create_func = create_semaphore_osx;
+}
+
+SemaphoreOSX::SemaphoreOSX() {
+
+	cgsem_init(&sem);
+}
+
+SemaphoreOSX::~SemaphoreOSX() {
+
+	cgsem_destroy(&sem);
+}