`__builtin_va_alist' undeclared (yes I know this is a FAQ)

[Chris Majewski]

I'm getting 

`__builtin_va_alist' undeclared (first use in this function)

when using va_start() and #include <varargs.h>. 

Admittedly, #include<stdarg.h> works,  but that's completely different
from what works on the SPARC boxes here, so I'd like to clear this up.

This is a gcc-2.95.2 I've just built on an x86-Solaris-2.8 box. 
I've seen a million references to this on deja but they all say "build
your own gcc". I've done that, and no juice. 

Output from `gcc -v' follows. 

-chris

gcc  -v -g -Wall -fPIC -DSunOS  -DMODULE_NAME=\"pam_sessask.so\"  -c sessask.c -o sessask.o 
Reading specs from /usr/local/lib/gcc-lib/i386-pc-solaris2.8/2.95.2/specs
gcc version 2.95.2 19991024 (release)
 /usr/local/lib/gcc-lib/i386-pc-solaris2.8/2.95.2/cpp -lang-c -v -D__GNUC__=2 -D__GNUC_MINOR__=95 -Dunix -D__svr4__ -D__SVR4 -Dsun -D__unix__ -D__svr4__ -D__SVR4 -D__sun__ -D__unix -D__sun -Asystem(svr4) -g -Wall -Acpu(i386) -Amachine(i386) -Di386 -D__i386 -D__i386__ -DSunOS -DMODULE_NAME="pam_sessask.so" sessask.c /var/tmp/ccteYI99.i
GNU CPP version 2.95.2 19991024 (release) (i386 System V Release 4)
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /usr/local/i386-pc-solaris2.8/include
 /usr/local/lib/gcc-lib/i386-pc-solaris2.8/2.95.2/include
 /usr/include
End of search list.
The following default directories have been omitted from the search path:
 /usr/local/lib/gcc-lib/i386-pc-solaris2.8/2.95.2/../../../../include/g++-3
End of omitted list.
 /usr/local/lib/gcc-lib/i386-pc-solaris2.8/2.95.2/cc1 /var/tmp/ccteYI99.i -quiet -dumpbase sessask.c -g -Wall -version -fPIC -o /var/tmp/cc66Oqcj.s
GNU C version 2.95.2 19991024 (release) (i386-pc-solaris2.8) compiled by GNU C version 2.95.2 19991024 (release).
sessask.c: In function `_sessTalk':
sessask.c:35: `__builtin_va_alist' undeclared (first use in this function)
sessask.c:35: (Each undeclared identifier is reported only once
sessask.c:35: for each function it appears in.)