contrib: shell scripts: add quotes around more variables

contrib/build-wine/sign.sh

@@ -2,7 +2,7 @@
 
 set -e
 
-here=$(dirname "$0")
+here="$(dirname "$0")"
 if [ -z "$WIN_SIGNING_PASSWORD" ]; then
     echo "password missing"
     exit 1

contrib/build-wine/unsign.sh

@@ -5,9 +5,9 @@ set -e
 
 PROJECT_ROOT="$(dirname "$(readlink -e "$0")")/../.."
 CONTRIB="$PROJECT_ROOT/contrib"
-here=$(dirname "$0")
+here="$(dirname "$0")"
 test -n "$here" -a -d "$here" || exit
-cd $here
+cd "$here"
 
 if ! which osslsigncode > /dev/null 2>&1; then
     echo "Please install osslsigncode"