Soong: Add build_error proto raw file to $(OUT_DIR).

Soong_ui produces a build_error raw file to $(OUT_DIR) where
the file contains a list of build action errors. Each build action
error represents an error raised by a command. The build_error file
is populated if there was a build error.

Bug: b/132969697
Test: Ran m for successful build. Introduced a broken build change,
      ran m and verified using printproto that build_error was
      generated successfully.

Change-Id: I690ca1778b4e56f144a3173ba1d16d8494c32c15
diff --git a/ui/status/Android.bp b/ui/status/Android.bp
index 901a713..34241ee 100644
--- a/ui/status/Android.bp
+++ b/ui/status/Android.bp
@@ -19,6 +19,7 @@
         "golang-protobuf-proto",
         "soong-ui-logger",
         "soong-ui-status-ninja_frontend",
+        "soong-ui-status-build_error_proto",
     ],
     srcs: [
         "kati.go",
@@ -41,3 +42,12 @@
         "ninja_frontend/frontend.pb.go",
     ],
 }
+
+bootstrap_go_package {
+    name: "soong-ui-status-build_error_proto",
+    pkgPath: "android/soong/ui/status/build_error_proto",
+    deps: ["golang-protobuf-proto"],
+    srcs: [
+        "build_error_proto/build_error.pb.go",
+    ],
+}