Include <stdlib.h> for the labs function.  Also add missing int
types to function prototypes.

These changes increase compatibility with future compilers which
do not support implicit function declarations nor implicit ints.
Both language features are no longer part of C as of C99.

Fixed upstream via:

commit edeb5682d5b046bc48abf1773eb99799c7962aa4
Author: Robert Jongbloed <robertj@voxlucida.com.au>
Date:   Sat Sep 21 10:58:13 2013 +0000

    Fixed a raft of issues with XCode 5 and Mountain Lion.

diff --git a/plugins/audio/G.722.2/AMR-WB/dec_lpc.c b/plugins/audio/G.722.2/AMR-WB/dec_lpc.c
index b52e23ff2746f76a..96b4f7e494bb312b 100644
--- a/plugins/audio/G.722.2/AMR-WB/dec_lpc.c
+++ b/plugins/audio/G.722.2/AMR-WB/dec_lpc.c
@@ -4,6 +4,7 @@
  *===================================================================
  */
 #include <math.h>
+#include <stdlib.h>
 #include "typedef.h"
 #include "dec_util.h"
 
diff --git a/plugins/audio/LPC_10/src/analys.c b/plugins/audio/LPC_10/src/analys.c
index 787ab8db665eabf1..8ac85f90d6221122 100644
--- a/plugins/audio/LPC_10/src/analys.c
+++ b/plugins/audio/LPC_10/src/analys.c
@@ -246,7 +246,7 @@ static integer c__1 = 1;
     extern /* Subroutine */ int onset_(real *, integer *, integer *, integer *
 	    , integer *, integer *, integer *, struct lpc10_encoder_state *);
     integer *osptr;
-    extern /* Subroutine */ placea_(integer *, integer *
+    extern /* Subroutine */ int placea_(integer *, integer *
 	    , integer *, integer *, integer *, integer *, integer *, integer *
 	    , integer *), dcbias_(integer *, real *, real *), placev_(integer 
 	    *, integer *, integer *, integer *, integer *, integer *, integer 
diff --git a/plugins/audio/LPC_10/src/synths.c b/plugins/audio/LPC_10/src/synths.c
index d56b1e91e986f677..8dcb0ee01877f7bb 100644
--- a/plugins/audio/LPC_10/src/synths.c
+++ b/plugins/audio/LPC_10/src/synths.c
@@ -185,7 +185,7 @@ static real c_b2 = .7f;
     extern /* Subroutine */ int deemp_(real *, integer *, struct lpc10_decoder_state *);
     real ratio;
     integer ipiti[16];
-    extern /* Subroutine */ bsynz_(real *, integer *, 
+    extern /* Subroutine */ int bsynz_(real *, integer *,
 	    integer *, real *, real *, real *, real *, struct lpc10_decoder_state *), irc2pc_(real *, real *
 	    , integer *, real *, real *);
     real g2pass;