gem5 build system improved

Encapsulated gem5-specific code into wrapper functions to separate the
build process (Fail: CMake, gem5: scons). Added some gem5-related FIXMEs.

Another CMake related FIXME added. +some cosmetics.

Change-Id: Id84b480127b1f13aed6a0ee97f3583f410d531c5

src/core/sal/gem5/Gem5Connector.cc

@@ -1,3 +1,4 @@
+#if 0
 #include "Gem5Connector.hpp"
 
 #include "base/trace.hh"
@@ -23,3 +24,5 @@ void Gem5Connector::restore(const std::string &path)
 
 	root->loadState(&cp);
 }
+
+#endif