Remove unnecessary 'extern's.

Change-Id: Iba2b3fb6ff88e504f1657b915120ae43d58a1e03
diff --git a/libc/include/android/dlext.h b/libc/include/android/dlext.h
index 37e4cde..ca3bd25 100644
--- a/libc/include/android/dlext.h
+++ b/libc/include/android/dlext.h
@@ -129,7 +129,7 @@
   struct android_namespace_t* library_namespace;
 } android_dlextinfo;
 
-extern void* android_dlopen_ext(const char* filename, int flag, const android_dlextinfo* extinfo)
+void* android_dlopen_ext(const char* filename, int flag, const android_dlextinfo* extinfo)
   __INTRODUCED_IN(21);
 
 __END_DECLS