Integrate the old libm/test/ subdir into the main build. It hasn't
been used in a long time causing the code to rot a bit. I've fixed
some of those, but it still fails for many ports, so it's disabled
by default. People who want to take a closer look can run:
$ make libm/test/test
* libc/include/stdlib.h (strtof): New prototype (from C99).
(strtodf): Changed from prototype to macro which redefines
to strtof.
* libc/stdlib/atof.c: Change documentation to refer to strtof
instead of strtodf.
* libc/stdlib/atoff.c (atoff): Change to call strtof instead of
strtodf.
* libc/stdlib/strtod.c (strtodf): Renamed to strtof.
(strtof): New function.
* libm/test/convert.c (test_strtodf): Renamed to test_strtof which
calls strtof.