Fix a guard style inconsistency in regexp-stack.h.

Fix a guard style inconsistency in regexp-stack.h.
Two spaces before the endif guard comment.

[Dean McNamee, 2009-05-04 19:31:05]

Lame, my fault.  I turned a /* */ comment into a // comment, and broke the lint.

[Dean McNamee, 2009-05-04 19:31:40]

On 2009/05/04 19:31:05, Dean McNamee wrote:
> Lame, my fault.  I turned a /* */ comment into a // comment, and broke the
lint.

TBR

[Erik Corry, 2009-05-04 19:34:04]

LGTM