simpleperf: add an explicit "simpleperf" target.

This lets us set up the aosp-simpleperf-release branch to just build
simpleperf.

Bug: http://b/128690014
Test: manual
Change-Id: Ida8c4df5f6563b050a1399028fac31e7d1737f52
diff --git a/simpleperf/Android.bp b/simpleperf/Android.bp
index f7fbc2d..be13420 100644
--- a/simpleperf/Android.bp
+++ b/simpleperf/Android.bp
@@ -350,7 +350,7 @@
         "simpleperf_static_libs",
     ],
     dist: {
-        targets: ["sdk", "win_sdk"],
+        targets: ["sdk", "win_sdk", "simpleperf"],
     },
     srcs: [
         "main.cpp",
@@ -454,7 +454,7 @@
         "simpleperf_static_libs",
     ],
     dist: {
-        targets: ["sdk", "win_sdk"],
+        targets: ["sdk", "win_sdk", "simpleperf"],
     },
     srcs: [
         "report_lib_interface.cpp",