SVN: SVN is not necessary and not recommended. SVN is the software the developers use for version control; the releases still contain hooks into SVN because we fail to remove them, but SVN’s absence will only cause an error message about svn not found and prevent the developer-only -run:version flag from working; it won’t affect the compiled code.
lprotocols: protocols is one of the Rosetta libraries that SCons is supposed to be building. Apparently it is failing to do so (probably because it can’t find GCC to build it with).
G++/gcc: We do not have a complete list of what versions and sub-versions work with which OSes and under which phases of the moon. Generally, version-specific issues show up as “internal compiler errors” midway through compilation (not the sort of errors you have mentioned), and those can usually be bypassed by lowering the -finline-limit flag argument. I use gcc 4.3.2 on ubuntu 8.04 and 4.4.5 on 10.10 with no problems.
If your problem is still “o: command not found” messages, the problem is that SCons isn’t finding gcc/g++. It is attempting to issue commands that look like
g++ -o build/src/release/linux/2.6/64/x86/gcc/pr... . If it can’t find g++, then that part of the command is truncated and it issues a nonsense command starting with o. So, the question is, why can’t SCons find g++? You can experiment with “which g++” to see where your computer thinks g++ is, then try to get SCons to find that. You may have luck with explicit choice of compiler version with “cxx_ver=#.#” on the scons command line. You may be able to copy tools/build/site.settings.topsail to tools/build/site.settings; the extra settings in that file give SCons extra pathing locations.