Changes the -heap_commit_increment and -cache_commit_increment options to no longer be strictly required to be smaller than all unit sizes, which made it a pain to change the increment size without also specifying every unit parameter, of which there are many. It was also impractical to raise the heap increment on UNIX due to the signal special heap's maximum size. Now, each unit simply caps its own increment size to a maximum of its unit size.
Also fixes a regression: an assert when using -no_vm_reserve.
Tested by running with "-no_vm_reserve -heap_commit_increment 8M -cache_commit_increment 8M".
Fixes #3507 (closed)