Fix build of libiax2. We will now distribute it with SFLphone

Since there are multiple versions and that the official site isn't maintained,
we took the iaxclient version and merged it in here. We'll try to keep in sync
with those repos, and maybe we could host an updated version, or contact
upstream to ask them to merge the newer code.

libs/README.libiax2

-Taken and merged from:
+Taken and merged from
+=====================
+
 
 https://iaxclient.svn.sourceforge.net/svnroot/iaxclient/trunk/
    `-> lib/libiax2
+
+
+Official SVN
+============
+
+The official SVN (browse + repos) is:
+
+  http://svncommunity.digium.com/
+
+but it seems unmaintained, and is behind the iaxclient's version.
+
+
+Internet Draft for IAX2 protocol
+================================
+
+http://tools.ietf.org/id/draft-guy-iax-03.txt
+
+
+Compilation and installation
+============================
+
+Run:
+-------------------------
+./gen.sh
+./configure --prefix=/usr
+make
+-------------------------
\ No newline at end of file

libs/libiax2/src/Makefile.am

 AM_CFLAGS = -Wall -O2
 AM_CFLAGS += -g -Wall -Wstrict-prototypes -I .
-AM_CFLAGS += -DDEBUG_SUPPORT -DLIBIAX
+AM_CFLAGS += -DLIBIAX
 AM_CFLAGS += -fsigned-char
+# -DDEBUG_SUPPORT (doesn't compile with it)
 # -DDEBUG_DEFAULT 
 AM_CFLAGS += $(UCFLAGS)