gas: undetected undefined symbol with .space

[Greg McGary]

Witness this:

---------------- undef.s -----------------------
undef: .space UNDEF
undefx4: .space UNDEF * 4
------------------------------------------------

I get expected results from with gas from binutils-2.11.2:

undef.s: Assembler messages:
undef.s:1: Error: .space specifies non-absolute value
undef.s:2: Error: undefined symbol UNDEF in operation

With latest gas in CVS, the `UNDEF * 4' passes without an error:

/1/home/gkm/undef.s: Assembler messages:
/1/home/gkm/undef.s:1: Error: .space specifies non-absolute value

This has been broken for a long time.  I have observed this bug in gas
built a snapshot dated as early as May of 2001.

Greg