Issue#414 and qemu_mutex_lock() API Conversion

[Vilhelm Gyda]

Hi,

I am new here, so I found some issues suitable for beginners at [1]. I
am currently looking at the API Conversion task of replacing
`qemu_mutex_lock()` and `qemu_mutex_unlock()` with `QEMU_LOCK_GUARD()`

After reading the macro definition of `QEMU_LOCK_GUARD()` and
`WITH_QEMU_LOCK_GUARD()`, I think I can replace an instance of
`qemu_mutex_(un)lock` at line 1065[2] and 1072[3] with
`WITH_QEMU_LOCK_GUARD(&rs->bitmap_mutex) {}`

Will this be an acceptable patch? Do I need to do anything else before
submitting(other than the checkpatch script)? How and what should I
test before submitting? This page[4] has some tests, but will running
all these be too much for a change this trivial?

Also, about this bite-sized issue[5]. @jsnow has commented to get in
touch about it. So, what should be my next step for working on this
issue?

Thanks,
Will

[1]: https://wiki.qemu.org/Contribute/BiteSizedTasks
[2]: 
https://gitlab.com/qemu-project/qemu/-/blob/master/migration/ram.c?ref_type=heads#L1065
[3]: 
https://gitlab.com/qemu-project/qemu/-/blob/master/migration/ram.c?ref_type=heads#L1072
[4]: https://wiki.qemu.org/Testing
[5]: https://gitlab.com/qemu-project/qemu/-/issues/414