HEADS UP - major libc surgery in HEAD.

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

    In preparation for supporting David Xu's 1:1 threading library as well
    as to bring us into conformance with other UNIXes, a major update to
    libc has been committed.  This update was ported from FreeBSD by
    David Rhodus with testing and review by David Xu and myself.

    The new libc should be completely compatible with older binaries, but
    it is quite possible that we've introduced a bug or two.  Please report
    any new weird application bugs to the bugs@ list.

    Basically what is going on here is that we are slowly removing our
    dependancy on a separate threaded libc (libc_r or libcr).  libc is
    being made natively thread safe, with weakly bound stubs for POSIX
    locking calls and other weak bindings for things that a threading
    library would have to override, So libc can be linked with or without
    a threading library. 

    It is our intention to support multiple threading libraries and,
    ultimately, to support async messaged syscalls.  This separation of
    libc's core from the threading implementation is an important step
    in that direction.

						-Matt