build scripts: (trivial) add quotes around some shell variables

contrib/build-wine/sign.sh

@@ -12,7 +12,7 @@ cd $here
 CERT_FILE=${CERT_FILE:-~/codesigning/cert.pem}
 KEY_FILE=${KEY_FILE:-~/codesigning/key.pem}
 if [[ ! -f "$CERT_FILE" ]]; then
-    ls $CERT_FILE
+    ls "$CERT_FILE"
     echo "Make sure that $CERT_FILE and $KEY_FILE exist"
 fi
 
@@ -38,5 +38,5 @@ for f in $(ls *.exe); do
         -t "http://timestamp.digicert.com/" \
         -in "$f" \
         -out "../signed/$f"
-    ls ../signed/$f -lah
+    ls "../signed/$f" -lah
 done

contrib/release.sh

@@ -166,7 +166,7 @@ done
 
 # the macos binary is built on a separate machine.
 # the file that needs to be copied over is the codesigned release binary (regardless of builder role)
-dmg=electrum-$VERSION.dmg
+dmg="electrum-$VERSION.dmg"
 if ! test -f "dist/$dmg"; then
     if [ ! -z "$RELEASEMANAGER" ] ; then  # RM
         fail "dmg is missing, aborting. Please build and codesign the dmg on a mac and copy it over."