Convert benchmarks/Android.mk to .bp

This could not be converted because it built the target into a specific
location (/data/caliperperf) that a test depended on and which soong
does not support. However, that test appears to be unowned and broken
and converting will not make the issue worse.

Also, removed the Android.mk file as that was only there to include the
benchmarks/Android.mk file.

Bug: 130204596
Bug: 122333008
Test: vogar --benchmark --classpath out/target/common/obj/JAVA_LIBRARIES/benchmarks_intermediates/classes.jar benchmarks.AdditionBenchmark
Change-Id: I8f4c6963c2f0cab6eb044083f75c887bfc796dfc
diff --git a/JavaLibrary.bp b/JavaLibrary.bp
index 5808d1d..e7e2d2d 100644
--- a/JavaLibrary.bp
+++ b/JavaLibrary.bp
@@ -202,6 +202,7 @@
     visibility: [
         "//art/build/apex",
         "//external/wycheproof",
+        "//libcore/benchmarks",
     ],
     defaults: ["libcore_java_defaults"],
     installable: true,
@@ -247,6 +248,7 @@
         "//art/build/apex",
         "//external/robolectric-shadows",
         "//external/wycheproof",
+        "//libcore/benchmarks",
     ],
     defaults: ["libcore_java_defaults"],
     installable: true,