Placement of signgam in libc instead of libm

Hi

While double some checking that all references used by the long double math
routines Jennifer are resolved when linking, we have found a small oddity.

The file libc/reent/signgam.c is implemented as follows:

int *
__signgam (void)
{
  return &_REENT_SIGNGAM(_REENT);
}

When TLS is enabled, the macro _REENT_SIGNGAM resolves to
_tls_gamma_signgam which is in the file libm/math/w_lgamma.c. This creates
the first reference from libc to libm that I have ever seen and requires
explicitly linking with -lm -lc when using lgamma().

Would anyone be opposed to moving this method to libm/math?

--joel