Add DESTDIR install target
diff --git a/bin/installmesa b/bin/installmesa
index 80fd8ef..fad0722 100755
--- a/bin/installmesa
+++ b/bin/installmesa
@@ -12,7 +12,7 @@
 INCLUDE_DIR="/usr/local/include"
 LIB_DIR="/usr/local/lib"
 
-
+if [ x$# == "x0" ] ; then
 echo
 echo "***** Mesa installation - You may need root privileges to do this *****"
 echo
@@ -33,7 +33,6 @@
 	LIB_DIR=${INPUT}
 fi
 
-
 echo
 echo "About to install Mesa header files (GL/*.h) in: " ${INCLUDE_DIR}/GL
 echo "and Mesa library files (libGL.*, etc) in: " ${LIB_DIR}
@@ -41,6 +40,10 @@
 
 read INPUT
 
+else
+INCLUDE_DIR=$1/include
+LIB_DIR=$1/lib
+fi
 
 # flags:
 #  -f = force