Take global GL lock when inside SwapBuffers & Start/EndFrameCapture

* If we don't have this lock, we can end up trampling serialisation
  as two threads try to serialise at once.

renderdoc/driver/gl/gl_driver.cpp

@@ -1030,6 +1030,7 @@ WrappedOpenGL::ContextData &WrappedOpenGL::GetCtxData()
 }
 
 // defined in gl_<platform>_hooks.cpp
+Threading::CriticalSection &GetGLLock();
 void MakeContextCurrent(GLWindowingData data);
 
 // for 'backwards compatible' overlay rendering
@@ -2330,6 +2331,8 @@ void WrappedOpenGL::StartFrameCapture(void *dev, void *wnd)
   if(m_State != WRITING_IDLE)
     return;
 
+  SCOPED_LOCK(GetGLLock());
+
   RenderDoc::Inst().SetCurrentDriver(RDC_OpenGL);
 
   m_State = WRITING_CAPFRAME;
@@ -2386,6 +2389,8 @@ bool WrappedOpenGL::EndFrameCapture(void *dev, void *wnd)
   if(m_State != WRITING_CAPFRAME)
     return true;
 
+  SCOPED_LOCK(GetGLLock());
+
   CaptureFailReason reason = CaptureSucceeded;
 
   GLWindowingData prevctx = m_ActiveContexts[Threading::GetCurrentID()];

renderdoc/driver/gl/gl_hooks_linux.cpp

@@ -1065,6 +1065,8 @@ __attribute__((visibility("default"))) void glXSwapBuffers(Display *dpy, GLXDraw
   if(OpenGLHook::glhooks.glXSwapBuffers_real == NULL)
     OpenGLHook::glhooks.SetupExportedFunctions();
 
+  SCOPED_LOCK(glLock);
+
   // if we use the GLXDrawable in XGetGeometry and it's a GLXWindow, then we get
   // a BadDrawable error and things go south. Instead we track GLXWindows created
   // in glXCreateWindow/glXDestroyWindow and look up the source window it was
@@ -1336,6 +1338,11 @@ const GLHookSet &GetRealGLFunctions()
   return OpenGLHook::glhooks.GetRealGLFunctions();
 }
 
+Threading::CriticalSection &GetGLLock()
+{
+  return glLock;
+}
+
 void MakeContextCurrent(GLWindowingData data)
 {
   OpenGLHook::glhooks.MakeContextCurrent(data);

renderdoc/driver/gl/gl_hooks_win32.cpp

@@ -705,6 +705,8 @@ private:
 
     if(w != NULL && glhooks.m_HaveContextCreation)
     {
+      SCOPED_LOCK(glLock);
+
       RECT r;
       GetClientRect(w, &r);
 
@@ -1307,6 +1309,11 @@ const GLHookSet &GetRealGLFunctions()
   return OpenGLHook::glhooks.GetRealGLFunctions();
 }
 
+Threading::CriticalSection &GetGLLock()
+{
+  return glLock;
+}
+
 void MakeContextCurrent(GLWindowingData data)
 {
   OpenGLHook::glhooks.MakeContextCurrent(data);