[ci] try using prebuilt cygwin camlp5

extra/azure-pipelines/build-windows.yml

@@ -40,7 +40,9 @@ jobs:
           curl.exe -fsSL -o cygwin-setup.exe --retry 3 $(CYGWIN_SETUP)
           Start-Process -FilePath "cygwin-setup.exe" -ArgumentList "-B -q -R $(CYG_ROOT) -l C:/tmp -s $(CYG_MIRROR) -P default -P make -P git -P zlib-devel -P rsync -P patch -P diffutils -P curl -P unzip -P tar -P m4 -P perl -P libpcre-devel -P mingw64-$(MINGW_ARCH)-zlib -P mingw64-$(MINGW_ARCH)-gcc-core -P mingw64-$(MINGW_ARCH)-pcre" -Wait
           curl.exe -fsSL -o "opam.tar.xz" --retry 3 https://github.com/fdopen/opam-repository-mingw/releases/download/0.0.0.2/opam$(ARCH).tar.xz
+          curl.exe -fsSL -o "camlp5.tar.xz" --retry 3 https://github.com/Simn/mingw64-camlp5/releases/download/rel710/mingw64-$(MINGW_ARCH)-camlp5-710-1.tar.xz
           & "$(CYG_ROOT)/bin/bash.exe" @('-lc', 'echo "$OLDPWD"')
+          & "$(CYG_ROOT)/bin/bash.exe" @('-lc', 'cd "$OLDPWD" && tar -C / -xfv camlp5.tar.xz')
           & "$(CYG_ROOT)/bin/bash.exe" @('-lc', 'cd "$OLDPWD" && tar -xf opam.tar.xz')
           & "$(CYG_ROOT)/bin/bash.exe" @('-lc', 'cd "$OLDPWD" && bash opam$(ARCH)/install.sh')
           & "$(CYG_ROOT)/bin/bash.exe" @('-lc', 'opam init mingw "https://github.com/fdopen/opam-repository-mingw.git#opam2" --comp 4.07.0+mingw$(ARCH)c --switch 4.07.0+mingw$(ARCH)c --auto-setup --yes 2>&1')

opam

@@ -21,7 +21,6 @@ remove: [make "uninstall" "INSTALL_DIR=%{prefix}%"]
 depends: [
   "ocaml"               {>= "4.02"}
   "ocamlfind"           {build}
-  "camlp5"              {build}
   "sedlex"              {build}
   "ppx_tools_versioned" {build & != "5.2.1"} #https://github.com/alainfrisch/sedlex/issues/64
   "xml-light"           {build}