plugins/cache: supported multicore cache modelling

plugins/cache: supported multicore cache modelling

Multicore L1 cache modelling is introduced and is supported for both
full system emulation and linux-user.

For full-system emulation, L1 icache and dcache are maintained for each
available core, since this information is exposed to the plugin through
`qemu_plugin_n_vcpus()`.

For linux-user, a static number of cores is assumed (default 1 core, and
can be provided as a plugin argument `cores=N`). Every memory access
goes through one of these caches, this approach is taken as it's
somewhat akin to what happens on real setup, where a program that
dispatches more threads than the available cores, they'll thrash
each other

Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Message-Id: <20210803151301.123581-2-ma.mandourr@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>