style: [patch 1/22] use /r/3648/ to reorganize includes

arch: Use const StaticInstPtr references where possible

This patch optimises the passing of StaticInstPtr by avoiding copying
the reference-counting pointer. This avoids first incrementing and
then decrementing the reference-counting pointer.

power: Remove unused private members to fix compile-time warning

Certain versions of clang complain about unused private members if
they are not used. This changeset removes such members from the
POWER-specific ProcessInfo struct to silence the warning.

Power: Add a stubbed out stacktrace.cc