Reduce by 2 the build elapse time (#2146)

In order to reduce the overall elapse time, CMake will build only with VS015 and MSBuild only with VS2017. Also, only the internal OpenSSL binaries are used, not anymore the external OpenSSL binaries. External downloading should stay in case one changes its mind.

appveyor.yml

@@ -71,12 +71,12 @@ environment:
     - builder: cmake
       vsver: 140
 
-    - builder: cmake
-      vsver: 150
+#    - builder: cmake
+#      vsver: 150
 
-    - builder: msbuild
-      vsver: 140
-      linkmode: shared
+#    - builder: msbuild
+#      vsver: 140
+#      linkmode: shared
 
     - builder: msbuild
       vsver: 150
@@ -398,16 +398,8 @@ build_script:
   - ps: |
       if ($env:builder -eq "cygwin")
       {
-          $LastExitCode=0;
           $cmd='bash.exe configure --everything --omit=PDF';iex "& $cmd"
-          if ($LastExitCode -ne 0) {
-            throw "$cmd failed with exit code $LastExitCode."
-          }
-          $LastExitCode=0;
           $cmd='make.exe -s';iex "& $cmd"
-          if ($LastExitCode -ne 0) {
-            throw "$cmd failed with exit code $LastExitCode."
-          }
       }
       if ($env:builder -eq "msbuild")
       {
@@ -442,10 +434,6 @@ build_script:
         $defs = "--config RelWithDebInfo"
         $defs+=" -G" + $generator;
         $defs+=" -DCMAKE_BUILD_TYPE=RelWithDebInfo";
-        if ($env:vsver -eq "150")
-        {
-            $defs+=" -DDISABLE_INTERNAL_OPENSSL=ON";
-        }
         $defs+=" -DENABLE_PDF=OFF";
         $defs+=" -DENABLE_NETSSL=ON";
         $defs+=" -DENABLE_NETSSL_WIN=ON";