numeric slightly revised fdlibm 5.3

[David G Hough at validlab.com]

A further slight revision has been place at
http://www.validlab.com/software/fdlibm53.tar.gz

The code is the same, but a configure script has been contributed by
Nelson Beebe.

The previous changes to pow and tan are described in the README:

What's new in FDLIBM 5.3?

CONFIGURE
        To build FDLIBM, edit the supplied Makefile or create
        a local Makefile by running "sh configure"
        using the supplied configure script contributed by Nelson Beebe

BUGS FIXED

    1. e_pow.c incorrect results when
        x is very close to -1.0 and y is very large, e.g.
        pow(-1.0000000000000002e+00,4.5035996273704970e+15) = 0
        pow(-9.9999999999999978e-01,4.5035996273704970e+15) = 0
        Correct results are close to -e and -1/e.

    2. k_tan.c error was > 1 ulp target for FDLIBM
        5.2: Worst error at least 1.45 ulp at
        tan(1.7765241907548024E+269) = 1.7733884462610958E+16
        5.3: Worst error 0.96 ulp

NOT FIXED YET

    3. Compiler failure on non-standard code
        Statements like
                    *(1+(int*)&t1) = 0;
        are not standard C and cause some optimizing compilers (e.g. GCC)
        to generate bad code under optimization.    These cases
        are to be addressed in the next release.