(Follow-up to previous commit, q.v.) Looks as if downloading OpenWATC…

…OM 1.9 from openwatcom.org takes about two minutes. We only allowed about one minute. Reset --max-time=600 (ten minutes, for margin).

appveyor.yml

@@ -205,7 +205,7 @@ environment:
 init:
   - echo BUILD_NUMBER=%APPVEYOR_BUILD_NUMBER%
   # curl defaults --keepalive-time 60 --max-time ?? about 10 minutes --connect-timeout ??
-  - set CURL_ARGS=--location --fail --show-error --keepalive-time 10 --connect-timeout 10 --max-time 60
+  - set CURL_ARGS=--location --fail --show-error --keepalive-time 10 --connect-timeout 10 --max-time 600
   # Setup TOOLCHAIN for Visual Studio build tools
   - if not DEFINED TOOLCHAIN (
       if "%APPVEYOR_BUILD_WORKER_IMAGE%" == "Visual Studio 2015" (