The error logged in config.log with cc on Tru64unix is here.

cc: Error: conftest.c, line 80: In this statement, the declaration for the proto
typed intrinsic function "sigsetjmp" is incorrect: the declared return type of "
char" is not consistent with the expected type of "int". (intrinsicdecler)
char sigsetjmp ();
-----^

Apparently, this test program is wrong in many ways.  Autoconf system should be modified, I suppose.  Not only function names but also function prototypes should be checked.

The simplest fix for configure is at the end.  I know this is not controllable from wget project, but from autoconf.

So I had prepared the previous patch for utils.c, as you know.

I realized that gcc on tru64unix allow the current source to compile.  You can simply note that we have to use gcc on tru64unix in order to avoid the bug of autoconf.

=====
--- configure.org       2008-06-30 10:41:15.000000000 +0900
+++ configure   2008-09-14 08:27:09.000000000 +0900
@@ -8856,7 +8856,7 @@
 #ifdef __cplusplus
 extern "C"
 #endif
-char $ac_func ();
+int $ac_func ();
 /* The GNU C library defines this for functions which it implements
     to always fail with ENOSYS.  Some functions are actually named
     something starting with __ and the normal name is an alias.  */

Actually tru64unix supports sigsetjmp() and a modification for utils.c should not be necesary.  However, the configure script somehow decides sigsetjmp() is not available, then the issue around siggetmask() arises.  As a workaround I use attached patch.  I don't follow the discussion, but how about using this patch?

(file #15954)

siggetmask (used in utils.c) is an obsolete BSDism, and should not be used (also, Tru64 and VMS lack it); POSIX has sigprocmask(), which we should prefer if available; otherwise we should use nothing.

Thanks to Steven M Schweda for this issue.