Use target.linux for all linux kernel based targets

Now in Android.bp files, target.linux applies to all targets running a
linux kernel (android, linux_glibc, linux_bionic). So common
flags/sources/etc can be combined instead of copying them to each
target.

Test: m
Change-Id: If7ad138ea1c540c160731f86b6ccc0daa5c69b83
diff --git a/libutils/tests/Android.bp b/libutils/tests/Android.bp
index 6911fc5..a891fca 100644
--- a/libutils/tests/Android.bp
+++ b/libutils/tests/Android.bp
@@ -34,8 +34,6 @@
     target: {
         android: {
             srcs: [
-                "Looper_test.cpp",
-                "RefBase_test.cpp",
                 "SystemClock_test.cpp",
             ],
             shared_libs: [
@@ -46,7 +44,7 @@
                 "libbase",
             ],
         },
-        linux_glibc: {
+        linux: {
             srcs: [
                 "Looper_test.cpp",
                 "RefBase_test.cpp",