Automatically include <android/ndk-version.h> from every header.
(Via <sys/cdefs.h>, which is where we get <android/api-level.h> from.)
Not super helpful today, but when NDK r21 is the oldest NDK anyone cares
about, they'll be able to stop worrying about this specific header as
long as they've included _something_.
Test: builds
Change-Id: Ia5bc42f89b7025d8e3963e4fd590f0e3723157be
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index dceb116..689b650 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -361,3 +361,6 @@
#include <android/versioning.h>
#include <android/api-level.h>
+#if __has_include(<android/ndk-version.h>)
+#include <android/ndk-version.h>
+#endif