doxygen: enable AUTOBRIEF, drop \brief

Especially for short descriptions, it is annoying to have to type \brief for
every single API doc.

Drop all \brief and enable the AUTOBRIEF feature of doxygen, which always takes
the first sentence of an API doc as the brief description.

Change-Id: I11a8a821b065a128108641a2a63fb5a2b1916e87
diff --git a/include/osmocom/core/select.h b/include/osmocom/core/select.h
index c2b51a4..fe84c5b 100644
--- a/include/osmocom/core/select.h
+++ b/include/osmocom/core/select.h
@@ -8,17 +8,17 @@
  */
 
 /*! \file select.h
- *  \brief select loop abstraction
+ *  select loop abstraction
  */
 
-/*! \brief Indicate interest in reading from the file descriptor */
+/*! Indicate interest in reading from the file descriptor */
 #define BSC_FD_READ	0x0001
-/*! \brief Indicate interest in writing to the file descriptor */
+/*! Indicate interest in writing to the file descriptor */
 #define BSC_FD_WRITE	0x0002
-/*! \brief Indicate interest in exceptions from the file descriptor */
+/*! Indicate interest in exceptions from the file descriptor */
 #define BSC_FD_EXCEPT	0x0004
 
-/*! \brief Structure representing a file dsecriptor */
+/*! Structure representing a file dsecriptor */
 struct osmo_fd {
 	/*! linked list for internal management */
 	struct llist_head list;