Add std::terminate to ldso whitelist.

Due to recent changes on the Fiasco.OC platform, when building ldso
applications for this platform the std::terminate function is needed
by the ~Ipc_server destructor. So we've to add it to ldso's whitelist.

os/src/lib/ldso/symbol.map

@@ -50,6 +50,8 @@
 		/* GNU verbose terminate handler */
 		extern "C++" { __gnu_cxx::__verbose_terminate_handler*; };
 
+		extern "C++" { std::terminate*; };
+
 		/* x86 */
 		__cxa*;
 		_Unwind_Resume;