Fix tr1 and pty.h compilation issues

	* configure.ac: Check for tr1/unordered_map, tr1/memory
	and tr1/tuple, and their boost::tr1 counterparts.
	Check for pty.h, util.h and libutil.h.
	* src/common/nmv-log-stream.cc: Replace checks on compiler
	defined macros with checks for required headers; in this
	case tr1/unordered_map and boost/tr1/unordered_map.hpp.
	* src/dbgengine/nmv-dbg-common.h: Check whether tr1/memory
	or boost/tr1/memory.hpp is available and use accordingly.
	* src/dbgengine/nmv-var-list-walker.cc (SafePtrCmp::operator()):
	Compare method const-correctness.
	* src/dbgengine/nmv-var-walker.cc (SafePtrCmp::operator()):
	Compare method const-correctness.
	* src/langs/nmv-cpp-ast.h: Replace checks on compiler
	defined macros with checks for required headers; in this
	case tr1/memory and boost/tr1/memory.hpp.
	Rearrange various class definitions to make the compiler
	aware of the class hierarchy ahead of forward-declaring
	shared_ptr typedefs.
	* src/persp/dbgperspective/nmv-find-text-dialog.h: Use
	SafePtr, ObjectRef and ObjectUnref from nemiver::common.
	* src/uicommon/nmv-terminal.cc: Check whether tr1/tuple or
	boost/tr1/tuple.hpp is available and use accordingly.
	Replace checks on platform defined macros with checks for
	required headers; in this case pty.h, util.h and libutil.h.
	* src/common/nmv-proc-utils.cc: Replace checks on
	platform defined macros with checks for required headers;
	in this case pty.h, util.h and libutil.h.