[Development] Proposing to add (CPU) architecture maintainers

[Marc Mutz]

Hi,

I'm hitting a wall on architecture-specific patches that aren't x86 (or, 
to a lesser extent, ARM). I don't know who's responsible for the MIPS 
assembly we have in QtCore,  nor who to talk to to get qYieldCpu 
implemented for architectures other than x86 and ARM 
(https://bugreports.qt.io/browse/QTBUG-103010).

Honestly, I also feel that x86 gets dis-proportionally more love than 
other archs (incl. ARM), because Intel supports Thiago's work (whether 
by paying for his work or just by having access to experts, I don't want 
to speculate here, as it doesn't matter in the end).

So, I'd like to propose to create a set of CPU architecture maintainers 
a la the platform maintainers we already have. As per 
qprocessordetection.h, we purport to support the following architectures:

- Alpha (commented out, architecture is dead, anyway)
- ARM
- AVR32 (commented out)
- Blackfin (commented out)
- x86 (incl. AMD64)
- Itanium (architecture is dead, though)
- MIPS
- POWER
- RISC-V
- S390/X
- SuperH (commented out)
- Sparc
- WebAssembly (special case: archtecture == platform)

So, we'd need maintainers for the following platforms, or declare the 
platform unsupported:

- ARM
- x86 (Thiago would be the obvious candidate, if he's in for it)
- MIPS
- POWER
- RISC-V
- S390
- Sparc

I would expect maintainers to be comfortable approving[1] assembly code 
for their platform, work (or orchestrate work) towards feature-parity 
with Qt's x86 support, and ideally getting the architecture into our CI 
or else making sure locally that the architecture builds and tests pass.

[1] Maintainers need to be Approvers, but I think we can grow an 
architecture maintainer into a Qt project Approver, because I don't 
think we'll find arch maintainers for all archs from the current set
of Approvers.

What do you think?

Thanks,
Marc