Timothy Gu 6215ba804e Add preprocessor support for additional architectures
- _M_ARM is used by Microsoft [1]
- __riscv and __riscv_xlen are defined by [2]
- __sparc and __sparc__ are documented at [3]
- __MIPSEB__, __PPC__, __PPC64__ are documented at [3] and used in
  Chromium's build/build_config.h [4]
  Note: Chromium assumes that all PowerPC architectures are 64-bit. This
  is in fact not true.

[1]: https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=msvc-160
[2]: feca479356 (cc-preprocessor-definitions)
[3]: https://sourceforge.net/p/predef/wiki/Architectures/
[4]: https://source.chromium.org/chromium/chromium/src/+/master:build/build_config.h;drc=e12bf2e5ff1eacb9aca3e9a26bdeebdbdad5965a

Change-Id: I7d0176c38102e5e4cf0fcbe9b06a3520a79b0d71
Bug: webrtc:12312
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/198241
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Timothy Gu <timothygu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#32897}
2020-12-31 21:14:27 +00:00
..
2018-06-19 14:00:39 +00:00