libeffects: Added standalone testbench that calculates SNR value

Added a standalone test bench that calculates SNR values using 2 files
as input. This tool is used to test the multichannel changes.

Test: build_and_run_all_unit_tests.sh
Bug: 121353611
Change-Id: I5e67d8113bace7872133f2e02d9ae7b9d90e61ff
diff --git a/media/libeffects/lvm/tests/Android.bp b/media/libeffects/lvm/tests/Android.bp
index 8ee807c..003ce9e 100644
--- a/media/libeffects/lvm/tests/Android.bp
+++ b/media/libeffects/lvm/tests/Android.bp
@@ -44,3 +44,16 @@
         "-Wextra",
     ],
 }
+
+cc_test {
+    name: "snr",
+    host_supported: false,
+
+    srcs: ["snr.cpp"],
+
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wextra",
+    ],
+}