x86, asm: Fix CFI macro invocations to deal with shortcomings in gas

gas prior to (perhaps) 2.16.90 has problems with passing non-
parenthesized expressions containing spaces to macros. Spaces, however,
get inserted by cpp between any macro expanding to a number and a
subsequent + or -. For the +, current x86 gas then removes the space
again (future gas may not do so), but for the - the space gets retained
and is then considered a separator between macro arguments.

Fix the respective definitions for both the - and + cases, so that they
neither contain spaces nor make cpp insert any (the latter by adding
seemingly redundant parentheses).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4CBDBEBA020000780001E05A@vpn.id2.novell.com>
Cc: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>