AppVeyor fails to build

[jonathandturner]

We got AppVeyor setup, but it looks like we're not quite there.

  = note: C:\projects\rls\target\debug\deps\libcurl_sys-f41d8c033e8614d1.rlib(libcurl_la-cookie.o): In function `Curl_cookie_add':
          C:/Users/appveyor/.cargo/registry/src/github.com-1ecc6299db9ec823/curl-sys-0.3.6/curl/lib/cookie.c:690: undefined reference to `strtok_r'
          C:/Users/appveyor/.cargo/registry/src/github.com-1ecc6299db9ec823/curl-sys-0.3.6/curl/lib/cookie.c:695: undefined reference to `strtok_r'
          C:\projects\rls\target\debug\deps\libcurl_sys-f41d8c033e8614d1.rlib(libcurl_la-netrc.o): In function `Curl_parsenetrc':
          C:/Users/appveyor/.cargo/registry/src/github.com-1ecc6299db9ec823/curl-sys-0.3.6/curl/lib/netrc.c:121: undefined reference to `strtok_r'
          C:/Users/appveyor/.cargo/registry/src/github.com-1ecc6299db9ec823/curl-sys-0.3.6/curl/lib/netrc.c:192: undefined reference to `strtok_r'

I hunted around and found this thread, which seemed related.: alexcrichton/curl-rust#92 In the thread, @alexcrichton doesn't seem to think there's an easy fix.

#148 points us at one possible fix, but it didn't seem to do the trick.

[alexcrichton]

Yeah this is something I fear that we just got wrong in the MinGW part of Rust, but there's not really much we can do about it at this point. My recommendation would be to do what curl-rust does on Appveyor: always install msvc rust and then add MinGW as a standard library (and compile with --target). That way the broken package, rust-mingw, won't be installed.

Also I think #148 may be an unintended pointer?

[jonathandturner]

This should be fixed as we've been working on AppVeyor for a while now