fix 32-bit ppc support in Firefox

[q66]

There are several issues here:

1. nodejs - nodejs 12.x does not build on 32-bit ppc #27 For now, this can be worked around by switching to nodejs-lts. (for cross-compiling it's a non-issue as node is a host dependency)
2. There's some C++ code paths that fail to compile.
3. rustc crashes when compiling style during native compilation; cross compiling however works. this has been fixed some time ago
4. WebRTC failed to build (could be disabled in worst case) worked around by disabling
5. Crashes on startup in xptcall

[q66]

I wrote fixes for the C++ failures: a6e4022 which also disable WebRTC on ppc32 as it's not easily fixable at this time.

It is now possible to cross-compile Firefox for 32-bit ppc from another environment (native compilation does not work as rustc crashes). However, it still segfaults upon launch, I managed to capture a backtrace: https://gist.github.com/q66/0aefa2d42a846cfceb84607f19018c86

I'm not quite sure what to do with this one.

[q66]

since nobody seems to care, closing as wontfix