So that you don't see identical messages "Could not restore NVRAM content from the given file."
Instead, one will mention nvram.bin and the other will mention pram.bin.
Result of running IWYU (https://include-what-you-use.org/) and
applying most of the suggestions about unncessary includes and
forward declarations.
Was motivated by observing that <thread> was being included in
ppcopcodes.cpp even though it was unused (found while researching
the use of threads), but seems generally good to help with build
times and correctness.
