Fix compilation issues on OS X - mainly #include file changes (Lars Immisch)

diff --git a/src/abis_nm.c b/src/abis_nm.c
index 9820d97..6909f78 100644
--- a/src/abis_nm.c
+++ b/src/abis_nm.c
@@ -26,7 +26,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <fcntl.h>
-#include <malloc.h>
+#include <stdlib.h>
 #include <libgen.h>
 #include <time.h>
 #include <limits.h>
diff --git a/src/gsm_utils.c b/src/gsm_utils.c
index b0594ae..0c25b28 100644
--- a/src/gsm_utils.c
+++ b/src/gsm_utils.c
@@ -22,7 +22,7 @@
  */
 
 #include <openbsc/gsm_utils.h>
-#include <malloc.h>
+#include <stdlib.h>
 #include <string.h>
 
 /* GSM 03.38 6.2.1 Charachter packing */
diff --git a/src/signal.c b/src/signal.c
index a7fc28e..4227c6d 100644
--- a/src/signal.c
+++ b/src/signal.c
@@ -19,7 +19,7 @@
  */
 
 #include <openbsc/signal.h>
-#include <malloc.h>
+#include <stdlib.h>
 #include <string.h>
 
 
diff --git a/src/telnet_interface.c b/src/telnet_interface.c
index 5ed9a0e..d812b17 100644
--- a/src/telnet_interface.c
+++ b/src/telnet_interface.c
@@ -20,7 +20,7 @@
 
 #include <sys/socket.h>
 #include <netinet/in.h>
-#include <malloc.h>
+#include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>