dist: tools: git-cache: bump version

adds OSX fixes for md5sum, flock

dist/tools/git/git-cache

@@ -40,6 +40,20 @@ _add() {
     set +e
 }
 
+if [ "$(uname)" = Darwin ]; then
+    _locked() {
+        local lockfile="$1"
+        shift
+
+        while ! shlock -p $$ -f $lockfile; do
+            sleep 0.2
+        done
+
+        $*
+
+        rm $lockfile
+    }
+else
     _locked() {
         local lockfile="$1"
         shift
@@ -49,6 +63,7 @@ _locked() {
         $*
         ) 9>"$lockfile"
     }
+fi
 
 update() {
     set -e
@@ -108,7 +123,7 @@ _check_commit() {
 }
 
 _remote_name() {
-    echo "$*" | md5sum | cut -d\  -f1
+    echo "$*" | git hash-object --stdin
 }
 
 _tag_to_sha1() {