Appveyor: download SSL only if it does not exist

appveyor.yml

@@ -63,7 +63,7 @@ install:
   # Get OpenSSL
   - if not exist C:\ssl\ (md C:\ssl\)
   - if not exist C:\ssl\Win32OpenSSL.exe (curl http://slproweb.com/download/Win32OpenSSL-1_0_2d.exe -o C:\ssl\Win32OpenSSL.exe)
-  - if not exist C:\ssl\Win32OpenSSL.exe (curl http://slproweb.com/download/Win64OpenSSL-1_0_2d.exe -o C:\ssl\Win64OpenSSL.exe)
+  - if not exist C:\ssl\Win64OpenSSL.exe (curl http://slproweb.com/download/Win64OpenSSL-1_0_2d.exe -o C:\ssl\Win64OpenSSL.exe)
   - C:\ssl\Win32OpenSSL.exe /SILENT /LOG="C:\ssl\install32.log"
   - C:\ssl\Win64OpenSSL.exe /SILENT /LOG="C:\ssl\install64.log"