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}

test/testsupport/file_utils_unittest.cc

@@ -173,8 +173,9 @@ TEST_F(FileUtilsTest, ResourcePathReturnsCorrectPath) {
 #endif
 
   ASSERT_THAT(result, EndsWith(expected_end));
-  ASSERT_TRUE(FileExists(result)) << "Expected " << result << " to exist; did "
-                                  << "ResourcePath return an incorrect path?";
+  ASSERT_TRUE(FileExists(result)) << "Expected " << result
+                                  << " to exist; did "
+                                     "ResourcePath return an incorrect path?";
 }
 
 TEST_F(FileUtilsTest, ResourcePathFromRootWorkingDir) {