ci: Do not attempt download from not existing URL

It just waste time trying.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>

Author: freddy77

misc/appveyor.yml

@@ -123,8 +123,7 @@ install:
   # if cache doesn't have it, download it
   - >
     if not exist C:\Windows\gperf.exe (
-    (curl -L -o %TEMP%\gperf.zip http://kent.dl.sourceforge.net/project/gnuwin32/gperf/3.0.1/gperf-3.0.1-bin.zip && 7z e %TEMP%\gperf.zip -oC:\Windows bin\gperf.exe)
-    || (curl -L -o %TEMP%\gperf.zip https://sourceforge.net/projects/gnuwin32/files/gperf/3.0.1/gperf-3.0.1-bin.zip/download# && 7z e %TEMP%\gperf.zip -oC:\Windows bin\gperf.exe)
+    (curl -L -o %TEMP%\gperf.zip https://sourceforge.net/projects/gnuwin32/files/gperf/3.0.1/gperf-3.0.1-bin.zip/download# && 7z e %TEMP%\gperf.zip -oC:\Windows bin\gperf.exe)
     || (curl -L -o %TEMP%\gperf.zip https://www.freetds.org/gperf-3.0.1-bin.zip && 7z e %TEMP%\gperf.zip -oC:\Windows bin\gperf.exe))
 
 build_script: