Concatenate string literals at compile time.

This CL was generated by running:
git ls-files | grep ".cc" | xargs perl -i -ne 'BEGIN {undef $/}; s/("[\s\n]*<<[\s\n]*")/" "/g; print;'; git cl format

After that I manually edited modules/audio_processing/gain_controller2.cc to preserve its original
formatting.

This primary benefit of this change is a small reduction in binary size.

Bug: None
Change-Id: I689fa7ba9c717c314bb167e5d592c3c4e0871e29
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/165961
Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30251}

modules/video_coding/codecs/h264/h264_encoder_impl.cc

@@ -378,7 +378,7 @@ int32_t H264EncoderImpl::Encode(
   if (!encoded_image_callback_) {
     RTC_LOG(LS_WARNING)
         << "InitEncode() has been called, but a callback function "
-        << "has not been set with RegisterEncodeCompleteCallback()";
+           "has not been set with RegisterEncodeCompleteCallback()";
     ReportError();
     return WEBRTC_VIDEO_CODEC_UNINITIALIZED;
   }