* tools: refactorize tools flags parsing.
Each SPIR-V tool was handing their own flag parsing. This PR
adds a new flag parsing utility that should be flexible enough
for our usage, but generic enough so it can be shared across tools while
remaining simple to use.
* cfg: replace cfg option parsing with the new one.
* change spirv-dis parsing + title + summary
* clang format
* flags: fix static init fiasco & remove help
Static initialization order is important, and was
working just by sheer luck.
Also removing the help generation tooling. It's less flexible than the
hand-written string, and making it as-good and as-flexible brings too
much complexity.
* review feedback
* Run the validator in the optimization fuzzers.
The optimizers assumes that the input to the optimizer is valid. Since
the fuzzers do not check that the input is valid before passing the
spir-v to the optimizer, we are getting a few errors.
The solution is to run the validator in the optimizer to validate the
input.
For the legalization passes, we need to add an extra option to the
validator to accept certain types of variable pointers, even if the
capability is not given. At the same time, we changed the option
"--legalize-hlsl" to relax the validator in the same way instead of
turning it off.
