libc: only provide an rlib.

[huonw]

libc: only provide an rlib.

There's absolutely no reason for libc to be offered as a dynamic
library.

[alexcrichton]

In general I don't think that we want to avoid dylibs once you've gotten past the standard library, but the dependencies underneath the standard library can in general be available only as rlibs.

[sfackler]

Travis failure looks legit

[alexcrichton]

Sneaky, sneaky. It looks like #14344 strikes again.

I've gotten around this in the past with:

// liblibc/lib.rs
#[doc(hidden)]
pub fn issue_14344_workaround() {}

// libstd/lib.rs
#[doc(hidden)]
pub fn issue_14344_workaround() {
    libc::issue_14344_workaround();
}