newlib under Linux, next version

[DJ Delorie]

as 2.8.1 (i586-pc-msdosdjgpp) doesn't like .type being used like that.
It mentioned something about it being used outside .def/.endef.
Could you perhaps define a global macro for it?  So that the
source ended up like this:

	.global SYM (_f_atan2)
	SOTYPE_FUNCTION(_f_atan2)

I actually started something with DLL_EXPORT(sym) for cygwin, but
discovered (the hard way) that dll exports didn't work that way, so I
never implemented it.  I did do DLL_IMPORT(sym) though, in
libc/include/sys/config.h