[dsymutil] Tablegenify option parsing

[dsymutil] Tablegenify option parsing

This patch reimplements command line option parsing in dsymutil with
Tablegen and libOption. The main motivation for this change is to
prevent clashes with other cl::opt options defined in llvm. Although
it's a bit more heavyweight, it has some nice advantages such as no
global static initializers and better separation between the code and
the option definitions.

I also used this opportunity to improve how dsymutil deals with
incompatible options. Instead of having checks spread across the code,
everything is now grouped together in verifyOptions. The fact that the
options are no longer global means that we need to pass them around a
bit more, but I think it's worth the trade-off.

Differential revision: https://reviews.llvm.org/D68361

llvm-svn: 373622