Windows build is failing due to missing libpthread

[ameyp]

Since the older version of gcc is no longer being used, I believe that the mingw32-libpthread-old package recommended in https://github.com/mozilla/rust/wiki/Note-getting-started-developing-Rust is no longer valid. With the latest gcc and that package, even a simple C program compilation and linking as gcc test.c -lpthread fails with ld.exe: cannot find -lpthread. The problem no longer occurs if the mingw32-pthreads-w32 package is installed instead.

I believe the wiki page needs to be updated to ask the user to install the mingw32-pthreads-w32 package instead.

[ameyp]

I believe this should no longer be an issue thanks to #11100 and #11013, but the documentation should probably still be updated.

[alexcrichton]

Closing, windows no longer depends on libpthread (large changes with the move to mingw-w64)