afh: Expand documentation of init function declarations.

It's not obvious why all of these are declared here, so explain this
in a bit more detail.

diff --git a/afh_common.c b/afh_common.c
index 6feb7c3565dc6ed1f9023ba4eb6ad6b19bcadd48..0d8d905c4a9c764097fa6e7acf6023c50454f958 100644 (file)
--- a/afh_common.c
+++ b/afh_common.c
@@ -16,7 +16,16 @@
 #include "afh.h"
 
 typedef void afh_init_func(struct audio_format_handler *);
-/* It does not hurt to declare init functions which are not available. */
+/*
+ * Declaration of the audio format handler init functions.
+ *
+ * These symbols are referenced in the afl array below.
+ *
+ * Most audio format handlers depend on an external library and are not
+ * compiled in if the library is not installed. Hence it is well possible that
+ * not all of these functions are defined. It does not hurt to declare them
+ * anyway, and this avoids another set of ifdefs.
+ */
 extern afh_init_func mp3_init, ogg_init, aac_afh_init, wma_afh_init,
        spx_afh_init, flac_afh_init, opus_afh_init;