Update the build system

I originally derived the Makefile from one found randomly
on the net. But now, I rewrote it based on the one found in
Asterisk tree.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

.gitignore

@@ -1,3 +1,4 @@
 *.o
+*.o.d
 *.so
 .*.swp

Makefile

@@ -1,30 +1,48 @@
 ASTSRC?=../asterisk
 
--include $(ASTSRC)/menuselect.makeopts $(ASTSRC)/menuselect.makedeps
-
-LOADABLE_MODS=chan_openbsc
 
 ASTTOPDIR=$(ASTSRC)
-INCLUDE=-I$(ASTSRC)/include -I/usr/local/include
 
+# Asterisk configure options
 ifneq ($(wildcard $(ASTSRC)/makeopts),)
   include $(ASTSRC)/makeopts
 endif
 
-ifeq ($(OSARCH),SunOS)
-  ASTLIBDIR=/opt/asterisk/lib
+# Need to replicate some of the Asterisk top makefile logic
+	# CFLAGS
+_ASTCFLAGS:=-I$(ASTTOPDIR)/include $(CONFIG_CFLAGS) $(COPTS)
+_ASTLDFLAGS:=$(CONFIG_LDFLAGS) $(LDOPTS)
+
+	# Link of shared objects
+ifneq ($(findstring darwin,$(OSARCH)),)
+  _ASTCFLAGS+=-D__Darwin__
+  SOLINK=-dynamic -bundle -Xlinker -macosx_version_min -Xlinker 10.4 -Xlinker -undefined -Xlinker dynamic_lookup -force_flat_namespace
 else
-  ASTLIBDIR=$(libdir)/asterisk
+# These are used for all but Darwin
+  SOLINK=-shared
+  ifneq ($(findstring BSD,$(OSARCH)),)
+    _ASTLDFLAGS+=-L/usr/local/lib
+  endif
+endif
+
+ifeq ($(OSARCH),SunOS)
+  SOLINK=-shared -fpic -L/usr/local/ssl/lib -lrt
 endif
-MODULES_DIR=$(ASTLIBDIR)/modules
+
+ifeq ($(OSARCH),OpenBSD)
+  SOLINK=-shared -fpic
+endif
+
+# Menuselect stuff
+-include $(ASTTOPDIR)/menuselect.makeopts $(ASTTOPDIR)/menuselect.makedeps
+
+# Modules rules
+MODULE_PREFIX=chan
+MENUSELECT_CATEGORY=CHANNELS
+MENUSELECT_DESCRIPTION=Channel Drivers
 
 all: _all
 
 include $(ASTTOPDIR)/Makefile.moddir_rules
 
-%.so: %.o
-	$(CC) -shared -o $@ $<
-
-%.o: %.c
-	$(CC) -fPIC $(INCLUDE) -DAST_MODULE=\"$*\" -o $@ -c $<