Only use string comparison for type_id when necessary.

See a83af3c "Fix use of Luabind classes across
shared library boundary." The commit notes already contain links to
descriptions and even code snippets, describing when this is necessary. This
patch basically copies the #if from boost.

luabind/typeid.hpp

@@ -19,6 +19,15 @@
 #  include <cxxabi.h>
 # endif // __GNUC__
 
+// See https://svn.boost.org/trac/boost/ticket/754
+# if (defined(__GNUC__) && __GNUC__ >= 3) \
+      || defined(_AIX) \
+      || (defined(__sgi) && defined(__host_mips)) \
+      || (defined(__hpux) && defined(__HP_aCC)) \
+      || (defined(linux) && defined(__INTEL_COMPILER) && defined(__ICC))
+#  define LUABIND_SAFE_TYPEID 
+# endif
+
 namespace luabind {
 
 # ifdef BOOST_MSVC
@@ -43,17 +52,29 @@ class type_id
 
     bool operator!=(type_id const& other) const
     {
+# ifdef LUABIND_SAFE_TYPEID
         return std::strcmp(m_id->name(), other.m_id->name()) != 0;
+# else
+        return *m_id != *other.m_id;
+# endif
     }
 
     bool operator==(type_id const& other) const
     {
+# ifdef LUABIND_SAFE_TYPEID
         return std::strcmp(m_id->name(), other.m_id->name()) == 0;
+# else
+        return *m_id == *other.m_id;
+# endif
     }
 
     bool operator<(type_id const& other) const
     {
+# ifdef LUABIND_SAFE_TYPEID
         return std::strcmp(m_id->name(), other.m_id->name()) < 0;
+# else
+        return m_id->before(*other.m_id);
+# endif
     }
 
     std::string name() const