Turn on -Wstring-concatenation

Test: presubmit
Bug: 175068488
Change-Id: If1d37f744412ac2064d8cece251b39066f0e86c0
diff --git a/cc/config/global.go b/cc/config/global.go
index a340e46..e1a7e38 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -224,8 +224,6 @@
 		"-Wno-pessimizing-move",                     // http://b/154270751
 		// New warnings to be fixed after clang-r399163
 		"-Wno-non-c-typedef-for-linkage", // http://b/161304145
-		// New warnings to be fixed after clang-r407598
-		"-Wno-string-concatenation", // http://b/175068488
 		// New warnings to be fixed after clang-r428724
 		"-Wno-align-mismatch", // http://b/193679946
 		// New warnings to be fixed after clang-r433403
@@ -259,6 +257,9 @@
 
 		// http://b/199369603
 		"-Wno-null-pointer-subtraction",
+
+		// http://b/175068488
+		"-Wno-string-concatenation",
 	}
 
 	IllegalFlags = []string{