Ensure bgfx::init() respects BGFX_RESET_FLIP_AFTER_RENDER (#3073)

This updates the behaviour of bgfx::init() to ensure that it
checks for the BGFX_RESET_FLIP_AFTER_RENDER flag.

src/bgfx.cpp

@@ -1913,6 +1913,7 @@ namespace bgfx
 		m_flipped = true;
 		m_debug   = BGFX_DEBUG_NONE;
 		m_frameTimeLast = bx::getHPCounter();
+		m_flipAfterRender = !!(m_init.resolution.reset & BGFX_RESET_FLIP_AFTER_RENDER);
 
 		m_submit->create(_init.limits.minResourceCbSize);