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/riff.c

@@ -21,6 +21,7 @@
 
 #include <stddef.h>
 #include "config.h"
+#include "config_components.h"
 #include "libavutil/macros.h"
 #include "avformat.h"
 #include "internal.h"