binder: consistent vendor #defines

There is mixed use of __ANDROID_VNDK__
and __ANDROID_VENDOR__, so make sure they
are set consistently.

This is only possible because the VNDK is
deprecated. Before this, __ANDROID_VNDK__
may be set without __ANDROID_VENDOR__ (and I
think some of the logic in libbinder was
probably wrong at that point).

Bug: N/A
Test: N/A
Change-Id: I9cf106ab8309520229ae9e23e7d5c42ab3e425cf
diff --git a/libs/binder/Stability.cpp b/libs/binder/Stability.cpp
index c432b3a..665dfea 100644
--- a/libs/binder/Stability.cpp
+++ b/libs/binder/Stability.cpp
@@ -73,6 +73,14 @@
     (void)setRepr(binder, getLocalLevel(), REPR_NONE);
 }
 
+// after deprecation of the VNDK, these should be aliases. At some point
+// all references to __ANDROID_VNDK__ should be replaced by __ANDROID_VENDOR__
+// but for right now, check that this condition holds because some
+// places check __ANDROID_VNDK__ and some places check __ANDROID_VENDOR__
+#if defined(__ANDROID_VNDK__) != defined(__ANDROID_VENDOR__)
+#error "__ANDROID_VNDK__ and __ANDROID_VENDOR__ should be aliases"
+#endif
+
 Stability::Level Stability::getLocalLevel() {
 #ifdef __ANDROID_APEX__
 #error "APEX can't use libbinder (must use libbinder_ndk)"