Add a way to use libraries from the Android tree

This patch adds a gn variable build_with_android which makes it possible
to use Android internal (i.e., non-NDK) libraries when Perfetto is being
built as a part of the Android tree.

Change-Id: I935582fa969ab230b9ab0ac7d392dfeace802b0e
diff --git a/Android.bp b/Android.bp
index 4b8b1b8..4e32744 100644
--- a/Android.bp
+++ b/Android.bp
@@ -64,6 +64,7 @@
     "libandroid",
     "liblog",
     "libprotobuf-cpp-lite",
+    "libutils",
   ],
   static_libs: [
     "libgtest_prod",
@@ -81,6 +82,9 @@
   defaults: [
     "perfetto_defaults",
   ],
+  cflags: [
+    "-DPERFETTO_BUILD_WITH_ANDROID",
+  ],
 }
 
 // GN target: //:perfetto
@@ -93,6 +97,7 @@
     "libandroid",
     "liblog",
     "libtraced_shared",
+    "libutils",
   ],
   defaults: [
     "perfetto_defaults",
@@ -893,6 +898,7 @@
     "libandroid",
     "liblog",
     "libtraced_shared",
+    "libutils",
   ],
   defaults: [
     "perfetto_defaults",
@@ -909,6 +915,7 @@
     "libandroid",
     "liblog",
     "libtraced_shared",
+    "libutils",
   ],
   defaults: [
     "perfetto_defaults",