*/version.h: define FF_API macros unconditionally

There is no reason to wrap them in #ifndef guards, they should only be
defined here and nowhere else. The define guards just add the
possibility to accidentally use the same FF_API name in different
libraries.

libavdevice/version.h

@@ -46,8 +46,6 @@
  * dropped at a future version bump. The defines themselves are not part of
  * the public API and may change, break or disappear at any time.
  */
-#ifndef FF_API_DEVICE_CAPABILITIES
 #define FF_API_DEVICE_CAPABILITIES (LIBAVDEVICE_VERSION_MAJOR < 60)
-#endif
 
 #endif /* AVDEVICE_VERSION_H */