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/binutils.tmpl

@@ -1,7 +1,7 @@
 # Template file for 'binutils'
 pkgname=binutils
 version=2.18
-distfiles="http://ftp.gnu.org/gnu/binutils/$pkgname-$version@.tar.bz2"
+distfiles="http://ftp.gnu.org/gnu/binutils/$pkgname-$version.tar.bz2"
 build_style=gnu_configure
 configure_args="--disable-werror --enable-shared --disable-multilib"
 make_install_target="tooldir=$XBPS_DESTDIR/$pkgname-$version/usr