configure: Use a separate config_components.h header for $ALL_COMPONENTS

This avoids unnecessary rebuilds of most source files if only the
list of enabled components has changed, but not the other properties
of the build, set in config.h.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/bit.c

@@ -18,6 +18,9 @@
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
+
+#include "config_components.h"
+
 #include "avformat.h"
 #include "internal.h"
 #include "libavcodec/get_bits.h"