Fix the target Linux builds of ART

When ART_TARGET_LINUX was set it would hit some pieces of dead code that
were using old defines i.e. `__ANDROID__`

Test: export ART_TARGET_LINUX=true
Test: source build/envsetup.sh
Test: lunch
Test: cd art && mma

Change-Id: I80102750192928606e0884d2b723a87ccb7d7e19
diff --git a/runtime/oat_file.cc b/runtime/oat_file.cc
index 404e5ce..bdf8b0e 100644
--- a/runtime/oat_file.cc
+++ b/runtime/oat_file.cc
@@ -719,7 +719,7 @@
     dlopen_handle_ = android_dlopen_ext(absolute_path.get(), RTLD_NOW, &extinfo);
 #else
     UNUSED(oat_file_begin);
-    static_assert(!kIsTargetBuild, "host_dlopen_handles_ will leak handles");
+    static_assert(!kIsTargetBuild || kIsTargetLinux, "host_dlopen_handles_ will leak handles");
     MutexLock mu(Thread::Current(), *Locks::host_dlopen_handles_lock_);
     dlopen_handle_ = dlopen(absolute_path.get(), RTLD_NOW);
     if (dlopen_handle_ != nullptr) {