Enable bazel profiling in soong_build.

Bazel is executed several times during the execution of soong_build.
For each bazel execution, generate a profile and save under the
BAZEL_METRICS_DIR which is defined in soong_ui.

Bug: b/174479924
Test: * USE_BAZEL_ANALYSIS=1 USE_BAZEL=1 m nothing and checked
        if the cquery and graph build bazel profiles were generated.
      * Verified that the generated bazel profiles were uploaded
        to the local dev metrics pipeline.

Change-Id: I3d20204484dc6c5a1525a5d3eec1d62cfb33535b
diff --git a/bazel/Android.bp b/bazel/Android.bp
index 0113726..d557be5 100644
--- a/bazel/Android.bp
+++ b/bazel/Android.bp
@@ -2,6 +2,7 @@
     name: "soong-bazel",
     pkgPath: "android/soong/bazel",
     srcs: [
+        "constants.go",
         "properties.go",
     ],
     pluginFor: [