Make this build on platforms with stack protection

Adapted from a Gentoo patch. I guess this actually builds now, but it
may be better to have a less hacky solution.

lsb-build/stub_libs/libc_main.c

@@ -1,8 +1,8 @@
 #include "config.h"
 
 #ifdef TARGET_LIBC_PROVIDES_SSP
+void __sprintf_chk() {} ;
 void __stack_chk_fail() {} ;
-void __stack_chk_fail_local() {} ;
 #endif
 
 void _Exit() {} ;

lsb-build/stub_libs/libc_nonshared.c

@@ -98,3 +98,7 @@ __libc_csu_fini (void)
 
   _fini ();
 }
+
+#ifdef TARGET_LIBC_PROVIDES_SSP
+void __stack_chk_fail_local (void) {}
+#endif