fix gnutls download (closes #122)

cmake_targets/tools/build_helper

@@ -205,10 +205,8 @@ install_gnutls_from_source(){
     cd /tmp 
     echo "Downloading gnutls archive"
     $SUDO rm -rf /tmp/gnutls-3.1.23.tar.xz* /tmp/gnutls-3.1.23
-    wget http://mirrors.dotsrc.org/gcrypt/gnutls/v3.1/gnutls-3.1.23.tar.xz
-    if [ $? -ne 0 ]; then
+    wget http://mirrors.dotsrc.org/gcrypt/gnutls/v3.1/gnutls-3.1.23.tar.xz || \
       wget ftp://ftp.gnutls.org/gcrypt/gnutls/v3.1/gnutls-3.1.23.tar.xz
-    fi
     if [ ! -f gnutls-3.1.23.tar.xz ]; then
       echo_error "Could not download gnutls source files"
       cd -