Do not use test_per_src in libs/gui

Since atest does not support test_per_src, remove test_per_src.
Additional files will require separate cc_test statements to be added.

Bug: none
Test: atest SurfaceParcelable_test
Change-Id: I8865488ad7bd45de9069d95ab2f2cf47c3e253c0
diff --git a/libs/gui/tests/Android.bp b/libs/gui/tests/Android.bp
index 01e90e0..02064c6 100644
--- a/libs/gui/tests/Android.bp
+++ b/libs/gui/tests/Android.bp
@@ -50,9 +50,12 @@
     ],
 }
 
-// Build a separate binary for each source file to $(TARGET_OUT_DATA_NATIVE_TESTS)/$(LOCAL_MODULE)
+// Build a separate binary to $(TARGET_OUT_DATA_NATIVE_TESTS)/$(LOCAL_MODULE)
+// This test has a main method, and requires a separate binary to be built.
+// To add move tests like this, just add additional cc_test statements,
+// as opposed to adding more source files to this one.
 cc_test {
-    name: "libgui_separate_binary_test",
+    name: "SurfaceParcelable_test",
     test_suites: ["device-tests"],
 
     clang: true,
@@ -61,7 +64,6 @@
         "-Werror",
     ],
 
-    test_per_src: true,
     srcs: [
         "SurfaceParcelable_test.cpp",
     ],