Added DEBUG swith to make all builds DEBUG builds.

./configure DEBUG will turn debugging on for all future
invocations of make.

configure

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 OUTPUT=xia.mk
 
@@ -18,6 +18,8 @@ echo NPROCS=$(($CORES * 2)) >> $OUTPUT
 
 echo XIADIR=$(pwd) >> $OUTPUT
 
+[ "$1" == "DEBUG" ] && echo "DEBUG=1" >> $OUTPUT
+
 cat >> $OUTPUT << EOF
 APIDIR=\$(XIADIR)/api
 BINDIR=\$(XIADIR)/bin