Explicitly mark main() as public in executables to avoid an HP-UX

ld warning.

plugins/sudoers/regress/logging/check_wrap.c

@@ -46,6 +46,8 @@ sudo_conv_t sudo_conv;		/* NULL in non-plugin */
 
 extern void writeln_wrap(FILE *fp, char *line, size_t len, size_t maxlen);
 
+__dso_public int main(int argc, char *argv[]);
+
 static void
 usage(void)
 {