cpplint: Cleanup errors

Cleanup errors from upstream cpplint in preparation
for moving art's cpplint fork to upstream tip-of-tree cpplint.

Test: cd art && mm
Bug: 68951293
Change-Id: I15faed4594cbcb8399850f8bdee39d42c0c5b956
diff --git a/compiler/common_compiler_test.h b/compiler/common_compiler_test.h
index 0683577..bcda41a 100644
--- a/compiler/common_compiler_test.h
+++ b/compiler/common_compiler_test.h
@@ -28,7 +28,7 @@
 
 namespace art {
 namespace mirror {
-  class ClassLoader;
+class ClassLoader;
 }  // namespace mirror
 
 class CompilerDriver;