The #[cfg()] was looking for 'arget_os' instead of 'target_os'.

unix: Add sendfile to platforms that support it

Merging 2 PRs together

Add more RTLD_* constants

linux: Add splice, tee, vmsplice

Use iOS nightlies instead of a pinned version

fixes the bitrig d_namlen compile error

Define _SC_PAGE_SIZE constants

According to POSIX, sysconf can take _SC_PAGESIZE or _SC_PAGE_SIZE,
which may be the same value.  This constant was define in "apple" as
equal to _SC_PAGESIZE, but not any of the other platforms.

Add definitions for _SC_PAGE_SIZE for all platforms which had
_SC_PAGESIZE defined. On all platforms but Android (Bionic), they are
the same value; on Android _SC_PAGE_SIZE has a different value.

Add abort

This is defined by the C standard to indicate abnormal program
terminaiton; it is defined to call raise(SIGABRT), and to not return.
This can be useful when panics are not an option, such as signal
handlers handling stack overflow.

musl: define nlink_t as u32/u64

musl: fix linkage of libc

I messed up the logic of the cfg during my rebase of #163 

musl: add support for mips/mipsel

Definitions for i686-unknown-linux-musl, arm and asmjs musl

I've tested x86 against C locally, but not arm or asmjs.
I added the arm definitions because asmjs's C is derived from arms.

Mysteriously, my locally-built musl does not contain a
definition for _SC_2_C_VERSION, so I just removed it.

stdbuild conditional change

Building with cargo doesn't necessarily imply this isn't a `stdbuild` libc. This logic is more consistent with the rest of the repo.

Renames "sunos" to "solaris" (as a part of PR to add Illumos support to Rust)

Add pthread_setname_np for NetBSD

Fixes #156

Bump to 0.2.6