Clean up build files

Follow up to aosp/1277469. Cleans up the build files.
Turns out the real issue was perfetto_host_executable()
obliterating the base configs when applying the forwarded ones.

Change-Id: I968d6efc134abe9c58d116ca167753fc5e7b6538
diff --git a/gn/BUILD.gn b/gn/BUILD.gn
index 91ae3c7..ba4ccbc 100644
--- a/gn/BUILD.gn
+++ b/gn/BUILD.gn
@@ -217,7 +217,10 @@
   visibility = whitelisted_protobuf_full_deps
   if (current_toolchain == host_toolchain) {
     if (perfetto_use_system_protobuf) {
-      public_configs = [ ":system_protobuf", ":system_protoc" ]
+      public_configs = [
+        ":system_protobuf",
+        ":system_protoc",
+      ]
     } else {
       public_deps = [ "${perfetto_protobuf_target_prefix}:protoc_lib" ]
     }
@@ -358,12 +361,12 @@
   ]
 
   if (!perfetto_use_system_protobuf) {
-      cflags += [
+    cflags += [
       # Using -isystem instead of include_dirs (-I), so we don't need to suppress
       # warnings coming from libprotobuf headers. Doing so would mask warnings in
       # our own code.
-        "-isystem",
-        rebase_path("../buildtools/protobuf/src", root_build_dir)
-      ]
+      "-isystem",
+      rebase_path("../buildtools/protobuf/src", root_build_dir),
+    ]
   }
 }