It appears we need -DSUNOS4_CC for both solaris and sunos4 templates.

Per report from Andrew Clark.

src/template/solaris

@@ -1,6 +1,6 @@
 if test "$GCC" != yes ; then
   CC="$CC -Xa"			# relaxed ISO C mode
-  CFLAGS="-v"			# -v is like gcc -Wall
+  CFLAGS="-v -DSUNOS4_CC"	# -v is like gcc -Wall
   if test "$enable_debug" != yes; then
     CFLAGS="$CFLAGS -O"		# any optimization breaks debug
   fi