tests: add API_REGISTER_STATE_CHECK

used to wrap API functions to ensure full environment consistency as
opposed to the renamed ASM_REGISTER_STATE_CHECK which is used with
assembly functions.
currently checks the FPU tag word in x86/x86_64 gcc builds to ensure
emms has been called.

Change-Id: Ie241772dbf903d33d516a1add4c8c6783f2e1490

test/encode_test_driver.cc

@@ -59,7 +59,7 @@ void Encoder::EncodeFrameInternal(const VideoSource &video,
   }
 
   // Encode the frame
-  REGISTER_STATE_CHECK(
+  API_REGISTER_STATE_CHECK(
       res = vpx_codec_encode(&encoder_,
                              video.img(), video.pts(), video.duration(),
                              frame_flags, deadline_));