New comment by pullmoll on void-packages repository

https://github.com/void-linux/void-packages/issues/12058#issuecomment-497937635
Comment:
Now trying to build rust for x86_64-musl with this patch:
```
--- rustc-1.35.0-src/vendor/libc/src/unix/notbsd/linux/mod.rs   2019-05-20 15:47:24.000000000 +0200
+++ rustc-1.35.0-src/vendor/libc/src/unix/notbsd/linux/mod.rs   2019-06-01 12:57:27.526582596 +0200
@@ -3,7 +3,7 @@
 pub type useconds_t = u32;
 pub type dev_t = u64;
 pub type socklen_t = u32;
-pub type pthread_t = c_ulong;
+pub type pthread_t = u64;
 pub type mode_t = u32;
 pub type ino64_t = u64;
 pub type off64_t = i64;
```
and see if that fixes building cargo.
I have no experience with rust and cargo so this patch may be plain stupid.