Reland "Make bionic_platform_headers available only for Bionic targets".

The triggering reason for this change is that the SDK snapshot
generation cannot readily handle header libraries that are required for
targets that the SDK itself isn't available for. However, these include
files shouldn't be used without Bionic anyway.

Relanding unchanged - the build problem was due to a split topic.

Test: m checkbuild (on aosp_taimen)
Test: m (on aosp_taimen_hwasan)
Test: atest CtsBionicTestCases
Test: lunch fvp-userdebug && mmm bionic
Bug: 152255951
Change-Id: Iaf49597ea265e6f2a042de5ee873238073b2e545
diff --git a/tests/mte_test.cpp b/tests/mte_test.cpp
index 8928805..ff8cde6 100644
--- a/tests/mte_test.cpp
+++ b/tests/mte_test.cpp
@@ -14,6 +14,10 @@
  * limitations under the License.
  */
 
+#include <sys/cdefs.h>
+
+#if defined(__BIONIC__)
+
 #include <gtest/gtest.h>
 
 #include <android-base/macros.h>
@@ -46,3 +50,5 @@
 TEST(mte_test, ScopedDisableMTE) {
   test_tag_mismatch();
 }
+
+#endif  // __BIONIC__