Fix ost startup scripts

execfile has been replaced by exec in Python 3

scripts/ost.in

@@ -47,7 +47,7 @@ if test -e "${OST_SCRIPT}" ; then
       fi
     done
     IFS="#"
-    $pyexec -c "execfile('$DNG_ROOT/@LIBDIR@/python@PYTHON_VERSION@/site-packages/ost/ost_startup.py')" "${OST_SCRIPT}" $opts
+    $pyexec -c "exec(open('$DNG_ROOT/@LIBDIR@/python@PYTHON_VERSION@/site-packages/ost/ost_startup.py').read())" "${OST_SCRIPT}" $opts
     RC=$?
 else
     opts=""
@@ -59,7 +59,7 @@ else
       fi
     done
     IFS="#"
-    $pyexec $interactive -c "execfile('$DNG_ROOT/@LIBDIR@/python@PYTHON_VERSION@/site-packages/ost/ost_startup.py')" $opts
+    $pyexec $interactive -c "exec(open('$DNG_ROOT/@LIBDIR@/python@PYTHON_VERSION@/site-packages/ost/ost_startup.py').read())" $opts
     RC=$?
 fi
 IFS=$OLDIFS

scripts/ost_startup.py.in

@@ -73,7 +73,7 @@ home = os.getenv('HOME') or os.getenv('USERPROFILE')
 _ostrc=os.path.join(home, '.ostrc')
 if os.path.exists(_ostrc):
   try:
-    exec(open(_ostrc))
+    exec(compile(open(_ostrc).read(), _ostrc, 'exec'))
   except Exception as e:
     print(e)
 PushVerbosityLevel(options.vlevel)