building rubinius using gcc 3.4.6

gcc -Ivm/external_libs/libtommath -Ivm/external_libs/libgdtoa -Ivm/external_libs/onig -Ivm/external_libs/libffi/include -Ivm/external_libs/libltdl -Ivm/test/cxxtest -Ivm -I. -I/usr/local/include
-pipe -Wall -Wno-deprecated -DHAS_EXECINFO -ggdb3 -O2 -Werror -DRBX_PROFILER -c -o vm/exception.o vm/exception.cpp 2>&1
In file included from vm/shared_state.hpp:12,
                 from vm/vm.hpp:19,
                 from vm/builtin/object.hpp:6,
                 from vm/builtin/exception.hpp:6,
                 from vm/exception.cpp:1:
vm/symboltable.hpp:10:29: tr1/unordered_map: No such file or directory
In file included from vm/shared_state.hpp:12,
                 from vm/vm.hpp:19,
                 from vm/builtin/object.hpp:6,
                 from vm/builtin/exception.hpp:6,
                 from vm/exception.cpp:1:
vm/symboltable.hpp:35: error: `std::tr1' has not been declared
vm/symboltable.hpp:35: error: expected initializer before '<' token
vm/symboltable.hpp:72: error: `SymbolMap' does not name a type
rake aborted!
Command failed with status (1): [gcc -Ivm/external_libs/libtommath -Ivm/ext...]