use AS_VAR_APPEND more rather than manually appending

git-svn-id: https://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk@1914 b68d4a1b-bc3d-0410-92ed-d4ac073336b7

urjtag/ChangeLog

@@ -3,6 +3,8 @@
   * acinclude.m4: Add a new AS_VAR_PREPEND helper.
   * configure.ac: Use AS_VAR_PREPEND rather than touching the var directly.
 
+  * configure.ac: Use AS_VAR_APPEND rather than touching the var directly.
+
 2011-06-23  Mike Frysinger  <vapier@gentoo.org>
 
   * src/cmd/Makefile.am: Tweak dependencies so things work from a fresh

urjtag/configure.ac

@@ -238,8 +238,8 @@ AS_IF([test "x$with_libftdi" != xno], [
       ])
     ])
   ])
-  LIBS="$LIBFTDI_LIBS $LIBS"
-  CPPFLAGS="$CPPFLAGS $LIBFTDI_CFLAGS"
+  AS_VAR_APPEND([LIBS], " $LIBFTDI_LIBS")
+  AS_VAR_APPEND([CPPFLAGS], " $LIBFTDI_CFLAGS")
   AC_CHECK_FUNC([ftdi_usb_open], [
     AC_DEFINE(HAVE_LIBFTDI, 1, [Define if you have libftdi])
     HAVELIBFTDI=yes