Build the FlexDLL objects manually on AppVeyor

VS2015 isn't supported by the binary release of FlexDLL.

appveyor.yml

@@ -40,9 +40,13 @@ cache:
 install:
   - mkdir "%OCAMLROOT%/bin/flexdll"
   - appveyor DownloadFile "http://alain.frisch.fr/flexdll/flexdll-bin-0.35.zip" -FileName "flexdll.zip"
+  - appveyor DownloadFile "http://alain.frisch.fr/flexdll/flexdll-0.35.tar.gz" -FileName "flexdll.tar.gz"
   - cinst 7zip.commandline
-  - 7za x -y flexdll.zip
-  - for %%F in (flexdll.h flexlink.exe flexdll*_msvc64.obj default_amd64.manifest) do copy %%F "%OCAMLROOT%\bin\flexdll"
+  - mkdir flexdll-tmp
+  - cd flexdll-tmp
+  - 7za x -y ..\flexdll.zip
+  - for %%F in (flexdll.h flexlink.exe default_amd64.manifest) do copy %%F "%OCAMLROOT%\bin\flexdll"
+  - cd ..
   # Make sure the Cygwin path comes before the Git one (otherwise
   # cygpath behaves crazily), but after the MSVC one.
   - set Path=C:\cygwin\bin;%OCAMLROOT%\bin\flexdll;%Path%

appveyor_build.sh

@@ -37,10 +37,17 @@ git submodule update --init flexdll
 
 cd $APPVEYOR_BUILD_FOLDER
 
+PREFIX="C:/Program Files/OCaml"
+
+tar -xzf flexdll.tar.gz
+cd flexdll-0.35
+make MSVC_DETECT=0 CHAINS=msvc64 support
+cp flexdll*_msvc64.obj "$PREFIX/bin/flexdll"
+cd ..
+
 cp config/m-nt.h config/m.h
 cp config/s-nt.h config/s.h
 
-PREFIX="C:/Program Files/OCaml"
 echo "Edit config/Makefile to set PREFIX=$PREFIX"
 sed -e "s|PREFIX=.*|PREFIX=$PREFIX|" -e "/\(BYTE\|NATIVE\)CCCOMPOPTS=./s/\r\?$/ -WX\0/" config/Makefile.msvc64 > config/Makefile
 #run "Content of config/Makefile" cat config/Makefile