Fix 'gerrit.sh restart' for relative paths

Trying to restart gerrit using

  gerrit/site/bin/gerrit.sh restart

failed with

  ** ERROR: Cannot locate gerrit.sh

as gerrit.sh internally changed the current directory to the gerrit
site, while still trying to invoke itself using $0. We add a fallback
to also look for $0 in the initial directory.

Change-Id: I8ba9306cf875aa4ec8e5bb8c693360dafdcd16b9

gerrit-pgm/src/main/resources/com/google/gerrit/pgm/gerrit.sh

@@ -175,6 +175,7 @@ if test -z "$GERRIT_SITE" ; then
     exit 1
 fi
 
+INITIAL_DIR=`pwd`
 if cd "$GERRIT_SITE" ; then
   GERRIT_SITE=`pwd`
 else
@@ -481,8 +482,13 @@ case "$ACTION" in
     if test -f "$GERRIT_SH" ; then
       : OK
     else
-      echo >&2 "** ERROR: Cannot locate gerrit.sh"
-      exit 1
+      GERRIT_SH="$INITIAL_DIR/$GERRIT_SH"
+      if test -f "$GERRIT_SH" ; then
+        : OK
+      else
+        echo >&2 "** ERROR: Cannot locate gerrit.sh"
+        exit 1
+      fi
     fi
     $GERRIT_SH stop $*
     sleep 5