We set the symbolizer in the clang vars files but not in gcc. That means that if you use --sanitize=address with toolchain gcc you get an error asking you to manually pass LLVM_SYMBOLIZER=path to scons. But if you are using the toolchain compiler, we should assume you want to use the toolchain llvm-symbolizer as well and just do that busy work for you.

Since gcc -print-prog-name=llvm-symbolizer just prints llvm-symbolizer at you without path-qualifiying it, we can't use the same solution. But for the toolchain, we know that it is in the same bin/ dir as the compiler, so we can either set it relative to the path of the vars file, or just set it based on toolchain_bindir. Alternatively, since we inject the toolchain into the PATH, maybe an unqualified llvm-symbolizer command is fine, and the error we give if LLVM_SYMBOLIZER isn't configured is overly-agressive?