Add Verbose/Debug option to make_memory_load in GC Benchmarking Infra

One of the scenarios in the GC Benchmarking Infra, which is labeled as _high_memory_, requires the use of a tool (named _make_memory_load.c_) to load the machine's memory to a specified percentage.

This tool has the capability of printing detailed messages on the current memory loading numbers, as well as other informative stats while running, which is very helpful for debugging. However, this hidden functionality can only be currently enabled by uncommenting the line `#define VERBOSE true` directly in the source file.

It is desirable to implement this Verbose/Debug mode directly as a command line argument to the tool instead.