Sync libc/stdlib with FreeBSD (ignoring jemalloc, pts, and gdtoa):

Sync libc/stdlib with FreeBSD (ignoring jemalloc, pts, and gdtoa):

-Add a64l(), l64a(), and l64a_r() XSI extentions.  These functions
convert between a 32-bit integer and a radix-64 ASCII string.

-Replace some syscalls with libc version.

-Remove advertising clause.

-alloca() cannot check if the allocation is valid; mention the
consequences.

-Include some verbage about not calling exit() from functions registered
by atexit().

-Use pthread mutexes where possible instead of libc spinlocks.

-Significantly reduce the memory leak as noted in the BUGS section of
setenv(3) by tracking the size of the memory allocated instead of using
strlen() on the current value.

-Prefer setenv() instead of putenv().

-Convert *env() calls to POSIX:
	-unsetenv returns an int.
	-putenv takes a char * instead of const char *.
	-putenv no longer makes a copy of the input string.
	-errno is set appropriately.  Exceptions involve bad environ
	variable and internal initialization code.  These both set errno
	to EFAULT.

-Make getopt_long() more GNU compatible and sync up with OpenBSD's
version.

-POSIX clearly states that getsubopt() should be declared in <stdlib.h>
not in <unistd.h>

-Use size_t to avoid overflow when sorting arrays larger than 2 GB in
heapsort() and qsort().

-Add new implementations of insque() and remque() which conform to
IEEE Std 1003.1-2001.

-Add qsort_r() for functions that need to be reentrant.

-Improve radixsort()'s preformance when sorting strings with common
prefixes.

-Use 'uint32_t' instead of 'long' when a 32-bit integer is intended in
random(3).

-Rearrange <stdlib.h> in a more logical order based on visibility.

-Move getsubopt()'s prototype to <stdlib.h> (standards).

-Make an internal _getprogname() that is used only inside
libc. For libc, getprogname(3) is a weak symbol in case a
function of the same name is defined in userland.