Count processor resources individually in MachineTraceMetrics.

The new instruction scheduling models provide information about the
number of cycles consumed on each processor resource. This makes it
possible to estimate ILP more accurately than simply counting
instructions / issue width.

The functions getResourceDepth() and getResourceLength() now identify
the limiting processor resource, and return a cycle count based on that.

This gives more precise resource information, particularly in traces
that use one resource a lot more than others.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178553 91177308-0d34-0410-b5e6-96231b3b80d8