Store forwarding benchmarks

[travisdowns]

Create benchmarks that investigate various aspects of store-forwarding behavior, such as:

• store->load forwarding latency
• misaligned load scenarios
• store->load throughput
• determine how far a load has to be from the aliasing store before store-forwarding apparently stops

[travisdowns]

Some of this was added in 0f54fa4dea423bad14af100521d47c7afcf45c67 although not all of the types mentioned above were covered.