fix reversed argument order x86_64 sigsetjmp's call to sigprocmask

this caused sigsetjmp not to save the signal mask but instead to
clobber it with whatever happened to be in the sigjmb_buf prior to the
call.
remove __STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS checks in stdint.h

C++11, the first C++ with stdint.h, requires the previously protected
macros to be exposed unconditionally by stdint.h. apparently these
checks were an early attempt by the C committee to guess what the C++
committee would want, and they guessed wrong.
Merge branch 'master' of git://git.musl-libc.org/musl into fixes