Use rustup to add targets, not manual curl

Add support for arm-unknown-linux-musleabi{,hf} targets.

These targets will be similar to the x86_64-unknown-linux-musl
target, in that they'll use MUSL libc to allow fully static binaries
to be generated. To remain consistent with the naming of existing
ARM targets, as well as with the standard naming of MUSL toolchains,
we'll use `musleabi` and `musleabihf` as the target environment
names (analogous to `gnueabi` and `gnueabihf`).

Most of these changes just extend the special casing for x86_64 MUSL
targets to the ARM ones as well.

These targets will be similar to the x86_64-unknown-linux-musl
target, in that they'll use MUSL libc to allow fully static binaries
to be generated. To remain consistent with the naming of existing
ARM targets, as well as with the standard naming of MUSL toolchains,
we'll use `musleabi` and `musleabihf` as the target environment
names (analogous to `gnueabi` and `gnueabihf`).

Most of these changes just extend the special casing for x86_64 MUSL
targets to the ARM ones as well.

Add ucontext for linux-musl.

It just copy pasted from the linux-other version.

Add the family of printf, scanf functions

snprintf is apparently supported in MSVC since version 14. I'm curious to take the tests for a spin.

64-bit Android timegm fix

On aarch64 and x86_64, `timegm64` does not exist (see [time64.h](https://android.googlesource.com/platform/development/+/797351fd3bbb8fe517afafdd5095fd740387e7a4/ndk/platforms/android-L/include/time64.h)).

See rust-lang-deprecated/time#118 for usage. Since that patch, the time library switched to using libc for `timegm` (rust-lang-deprecated/time@51c0019), and it doesn't build on 64-bit Android. This PR fixes that.

Bump to 0.2.10

Use '&&' on travis, not ';'

Closes #258

Fix CPU_SET and CPU_ISSET

Signed-off-by: NODA, Kai <nodakai@gmail.com>

Use now available link name "signal" instead of "bsd_signal"

On android, the `bsd_signal` is gone, the `signal` is available.

While this is the most obvious solution, I am not sure of a few things:
- How are we going to keep compatibility with older NDKs where `signal` does not exist;
- Was something dependent on this being different on android and thus would break (for example, the rust compiler uses this function, so it may break somewhere).

Fixes #236.

Remove iOS doc links from README

Fixes #243

langinfo bindings and defs

There are many constants defined by langinfo, but we have the
new types, locale_t and nl_item.

We also have several functions, not all of which exist for every
platform:

nl_langinfo
nl_langinfo_l
newlocale
duplocale
freelocale
uselocale
querylocale

Add RTLD_DEFAULT to more platforms

Link to libraries when disabling `use_std`

This crate currently relies on libraries being linked to come from libstd, but
if `use_std` is disabled that's not true! In that case we need to pull in the
libraries ourselves.

Closes rust-lang/rust#32661

This crate currently relies on libraries being linked to come from libstd, but
if `use_std` is disabled that's not true! In that case we need to pull in the
libraries ourselves.

Closes rust-lang/rust#32661

On non-musl Linux, strerror_r should be linked to __xpg_strerror_r

Currently `libc::strerror_r()` wrongly returns a `c_char` pointer as a large `c_int`.

Also exclude `MS_RMT_MASK` from `libc-test`.

Add several pthread functions for DragonFly/FreeBSD

These are needed in order to fix/implement the guard page code of Rust
for DragonFly.

Add clock_getres(3) and improve clockid_t constants.

This is still a draft

It was updated recently, so the test is known to fail depending on the
libc version of the test environment.

Signed-off-by: NODA, Kai <nodakai@gmail.com>

Signed-off-by: NODA, Kai <nodakai@gmail.com>

These are needed in order to fix/implement the guard page code of Rust
for DragonFly.

Signed-off-by: NODA, Kai <nodakai@gmail.com>

unix: Add openpty(3) and forkpty(3) for non-Apple platforms

The functions were added for Apple in #202. Adding them to other
platforms was pending an amendment to RFC 1291 to expand the scope of
libc to include libutil. The amendment was merged as
  https://github.com/rust-lang/rfcs/pull/1529

The functions were added for Apple in #202. Adding them to other
platforms was pending an amendment to RFC 1291 to expand the scope of
libc to include libutil. The amendment was merged as
  https://github.com/rust-lang/rfcs/pull/1529

Add lconv type, and locale support for UNIX

We have lconv struct, setlocale(), and localeconv(). Constants live
under notbsd for now.

Linux-likes have more locale categories than the BSDs (except for
musl). We define the common set of categories at the
src/unix/notbsd/mod.rs level, and leave the rest to the
platform-specific modules.