supplying _foo_r functions when -DREENTRANT_SYSCALLS_PROVIDED

[Patrick Mansfield]

Hi -

I am trying to build SPU with -DSIGNAL_PROVIDED, -DREENTRANT_SYSCALLS_PROVIDED,
and -DMISSING_SYSCALL_NAMES, since the SPU doesn't need reentrant calls
(no threading, no signals), and setting these defines can save some space
and time.

But with those defines, I end up with these undefined functions:

	_gettimeofday_r - in time.c
	_sbrk_r - mallocr.c
	_times_r - in clock.c
	_write_r - in __dprintf.c (don't know if this is an issue)

How should I fix these? Supply SPU specific defines for them? 

Or have generic defines for these if REENTRANT_SYSCALLS_PROVIDED is defined?

i.e. defines like:

#define _sbrk_r(ptr, incr)	sbrk(incr)

-- Patrick Mansfield