Build the CC/CXX/AR/LD/RANLIB map once and hand it to shell()->setEnv()
so the configure/make invocations don't have to repeat the same prefix
on every line. For the sudo make-install path the env still needs to
be on the command line (sudo strips the parent env), so the same map
is rendered into $envFlags and prepended there. Also adds RANLIB,
which the upstream Makefile honours.
