Support memory alignment tests for string_benchmark.cpp

Test: Manually verify that benchmark times are similar and add a unit test.
Change-Id: Idaaeb4c8c3629f797ffd8d0c86c8d7b7b9653181
diff --git a/benchmarks/Android.bp b/benchmarks/Android.bp
index 3f95aa1..0edba65 100644
--- a/benchmarks/Android.bp
+++ b/benchmarks/Android.bp
@@ -35,6 +35,17 @@
         "time_benchmark.cpp",
         "unistd_benchmark.cpp",
     ],
+    static_libs: ["libBionicBenchmarksUtils"],
+}
+
+cc_defaults {
+    name: "bionic-benchmarks-extras-defaults",
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+        "-Wunused",
+    ],
 }
 
 // Build benchmarks for the device (with bionic's .so). Run with:
@@ -63,3 +74,19 @@
         },
     },
 }
+
+cc_library_static {
+    name: "libBionicBenchmarksUtils",
+    defaults: ["bionic-benchmarks-extras-defaults"],
+    srcs: ["util.cpp"],
+    host_supported: true,
+}
+
+cc_test {
+    name: "bionic-benchmarks-tests",
+    defaults: ["bionic-benchmarks-extras-defaults"],
+    srcs: [
+        "tests/benchmark_test.cpp",
+    ],
+    static_libs: ["libBionicBenchmarksUtils"],
+}