The mismatch occurs on an edge. Previously it was assigned
the parent priority, now it is assigned to the child
priority.

This should make reuse from buildcaches or store more likely,
since most mismatches will be counted with "reused" priority.

We don't want to e.g. switch other attributes because we
cannot reuse an old installed runtime.

This is such that the version of the runtime would
not influence whether we should reuse a spec.

Compiler mismatches are considered for runtimes,
to avoid situations where compiling foo%gcc@9
brings in gcc-runtime%gcc@13 if gcc@13 is among
the available compilers

This should ensure that we do not reuse specs that
could be broken, as they expect the compiler to be
installed in a specific place.

This is to avoid differences on m1
with respect to x86_64 machines

This is to avoid differences on m1
with respect to x86_64