Add guest instruction count statistics collection and display

[grigory-rechistov]

Add a mechanism to count how many times each of simulated opcode got executed.

Requirements for a solution

• It should only be active when INSTR_STAT macro is defined. I.e., it should be conditionally built in.
• It should maintain an array of counters to keep statistics for individual opcodes. After every instruction is simulated, the corresponding counter should be incremented by one.
• At the end of simulation, the results table should be produced. It should look like this:

     Opcode    Count
     -------------------
     Nop       1000
     Halt         1
     Push      1234
     ...

• It can be implemented in a generic manner to support all variants of interpreters

After the implementation is ready, it will be nice to compare performance of two builds - interpreter with stats enabled and disabled, to see the performance overhead such collection creates.

[lisitsynSA]

I take it.

[grigory-rechistov]

Not done