Fix compile issues for C89 compilers.

[Stephen J. Turnbull]

Jeff Sparkes writes:

 > I compiled with -ansi successfully without changes.  (After I fixed the
 > error I had introduced.)

Does -ansi catch that error?  If not, it's not very useful, I suspect.

 > I didn't look at any warnings though.  I just tried with -std=c89
 > and it failed at line 1389 in lisp.h, which is
 > DECLARE_INLINE_HEADER.  It must turn off gcc extensions, wchi
 > aren't standard anyway.  :-)

There are also -std=g89 and -std=g99 IIRC, which permit use of GCC extensions.