fixes black flicker on rotating the device

fixes #838

instead of rendering ad libitum on the map thread, we are now driving rendering from the UI thread on iOS via the map.renderSync() function. There are still white bars during the rotation, but the general content of the view is kept visible.

- upgrades GLFW to 3.1
- removes swapped/needsSwap in favor of a more explicit scheme
- View#invalidate() now replaces View#swap() and is called whenever the View needs to trigger a rerender. GLFW and Android to this right away, while iOS goes back to the main thread and does the Map redrawing as part of the GLKView update
- sets all iOS deployment targets to 7.0
- disables SQLite3 version check, since the library version changed on iOS 8.2

android/cpp/jni.cpp

@@ -291,18 +291,11 @@ void JNICALL nativeRun(JNIEnv *env, jobject obj, jlong nativeMapViewPtr) {
     nativeMapView->getMap().run();
 }
 
-void JNICALL nativeRerender(JNIEnv *env, jobject obj, jlong nativeMapViewPtr) {
-    mbgl::Log::Debug(mbgl::Event::JNI, "nativeRerender");
-    assert(nativeMapViewPtr != 0);
-    NativeMapView *nativeMapView = reinterpret_cast<NativeMapView *>(nativeMapViewPtr);
-    nativeMapView->getMap().rerender();
-}
-
 void JNICALL nativeUpdate(JNIEnv *env, jobject obj, jlong nativeMapViewPtr) {
     mbgl::Log::Debug(mbgl::Event::JNI, "nativeUpdate");
     assert(nativeMapViewPtr != 0);
     NativeMapView *nativeMapView = reinterpret_cast<NativeMapView *>(nativeMapViewPtr);
-    nativeMapView->getMap().update();
+    nativeMapView->getMap().triggerUpdate();
 }
 
 void JNICALL nativeTerminate(JNIEnv *env, jobject obj, jlong nativeMapViewPtr) {
@@ -312,20 +305,6 @@ void JNICALL nativeTerminate(JNIEnv *env, jobject obj, jlong nativeMapViewPtr) {
     nativeMapView->getMap().terminate();
 }
 
-jboolean JNICALL nativeNeedsSwap(JNIEnv *env, jobject obj, jlong nativeMapViewPtr) {
-    mbgl::Log::Debug(mbgl::Event::JNI, "nativeNeedsSwap");
-    assert(nativeMapViewPtr != 0);
-    NativeMapView *nativeMapView = reinterpret_cast<NativeMapView *>(nativeMapViewPtr);
-    return nativeMapView->getMap().needsSwap();
-}
-
-void JNICALL nativeSwapped(JNIEnv *env, jobject obj, jlong nativeMapViewPtr) {
-    mbgl::Log::Debug(mbgl::Event::JNI, "nativeSwapped");
-    assert(nativeMapViewPtr != 0);
-    NativeMapView *nativeMapView = reinterpret_cast<NativeMapView *>(nativeMapViewPtr);
-    nativeMapView->getMap().swapped();
-}
-
 void JNICALL nativeResize(JNIEnv *env, jobject obj, jlong nativeMapViewPtr, jint width, jint height,
                           jfloat ratio, jint fbWidth, jint fbHeight) {
     mbgl::Log::Debug(mbgl::Event::JNI, "nativeResize");
@@ -1002,7 +981,7 @@ extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {
 
     // NOTE: if you get java.lang.UnsatisfiedLinkError you likely forgot to set the size of the
     // array correctly (too large)
-    std::array<JNINativeMethod, 66> methods = {{ // Can remove the extra brace in C++14
+    std::array<JNINativeMethod, 63> methods = {{ // Can remove the extra brace in C++14
         {"nativeCreate", "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)J",
          reinterpret_cast<void *>(&nativeCreate)},
         {"nativeDestroy", "(J)V", reinterpret_cast<void *>(&nativeDestroy)},
@@ -1018,11 +997,8 @@ extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {
         {"nativePause", "(J)V", reinterpret_cast<void *>(&nativePause)},
         {"nativeResume", "(J)V", reinterpret_cast<void *>(&nativeResume)},
         {"nativeRun", "(J)V", reinterpret_cast<void *>(&nativeRun)},
-        {"nativeRerender", "(J)V", reinterpret_cast<void *>(&nativeRerender)},
         {"nativeUpdate", "(J)V", reinterpret_cast<void *>(&nativeUpdate)},
         {"nativeTerminate", "(J)V", reinterpret_cast<void *>(&nativeTerminate)},
-        {"nativeNeedsSwap", "(J)Z", reinterpret_cast<void *>(&nativeNeedsSwap)},
-        {"nativeSwapped", "(J)V", reinterpret_cast<void *>(&nativeSwapped)},
         {"nativeResize", "(JIIFII)V",
          reinterpret_cast<void *>(static_cast<void JNICALL (
              *)(JNIEnv *, jobject, jlong, jint, jint, jfloat, jint, jint)>(&nativeResize))},

android/cpp/native_map_view.cpp

@@ -121,16 +121,17 @@ void NativeMapView::deactivate() {
     }
 }
 
-void NativeMapView::swap() {
-    mbgl::Log::Debug(mbgl::Event::Android, "NativeMapView::swap");
+void NativeMapView::invalidate() {
+    mbgl::Log::Debug(mbgl::Event::Android, "NativeMapView::invalidate");
+
+    if ((display != EGL_NO_DISPLAY) && (surface != EGL_NO_SURFACE)) {
+        map.render();
 
-    if (map.needsSwap() && (display != EGL_NO_DISPLAY) && (surface != EGL_NO_SURFACE)) {
         if (!eglSwapBuffers(display, surface)) {
             mbgl::Log::Error(mbgl::Event::OpenGL, "eglSwapBuffers() returned error %d",
                              eglGetError());
             throw new std::runtime_error("eglSwapBuffers() failed");
         }
-        map.swapped();
         updateFps();
     } else {
         mbgl::Log::Info(mbgl::Event::Android, "Not swapping as we are not ready");