Add target for "make splint". A few files need extra guards to avoid

errors on systems where they would not otherwise be compiled.
No warnings from splint.

plugins/sudoers/solaris_audit.c

@@ -16,6 +16,8 @@
 
 #include <config.h>
 
+#ifdef HAVE_SOLARIS_AUDIT
+
 #include <sys/types.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -123,3 +125,5 @@ solaris_audit_failure(int argc, char *argv[], char const *const fmt, va_list ap)
 
 	return 0;
 }
+
+#endif /* HAVE_SOLARIS_AUDIT */