Use bash features to improve $distfiles parsing.

That means that it's not necessary anymore to use an '@' before the
extract suffix string. yay.

--HG--
extra : convert_revision : 83ce2c783cb917ef59b87eacb0565cfcff277218

templates/babl.tmpl

@@ -1,7 +1,7 @@
 # Template build file for 'babl'.
 pkgname=babl
 version=0.0.22
-distfiles="ftp://ftp.gtk.org/pub/babl/0.0/$pkgname-$version@.tar.bz2"
+distfiles="ftp://ftp.gtk.org/pub/babl/0.0/$pkgname-$version.tar.bz2"
 build_style=gnu_configure
 make_cmd="$XBPS_MASTERDIR/bin/gmake"
 pkgconfig_override="babl.pc"