[VeriblePreProcessor][2]: Positional arguments to pass defines and inclusion directories.

[karimtera]

NOTE: This is a part of the sequentially splitted PRs from PR #1360.

Description:
This PR implements a class that handles positional arguments for the preprocessor tool.
Any of the following positional argument can be passed one or more times.

Argument	Description
<file.sv>	Specifies a SV file to be preprocessed.
+define+<foo>[=<text>]	Defines one or more macros same as `define foo text
+incdir+<dir>	Specifies the directory to search for files included with `include "file_name"

[hzeller]

I think if we use your code to parse things into a struct FileList (and add a container in there for the defines), we have a good starting point to use it for all tools.

[hzeller]

Nice. Make sure to add a unit test. Also, use absl::string_view where possible, avoid std::string unless you actually need a copy of the data.

[hzeller]

Here the first start would of course to rebase to current head.

But since there are a lot of changes that you essentially have to integrate, and this one is a somewhat independent (just the commandline changes), it might be easier if you start a fresh pull request: you just copy over the verilog_project.h, verilog_project.cc and verilog_project_test.cc as well as relevant BUILD rules over from here into a fresh fork from head and create a fresh pull request from that (and abandon this)

Up to you.

[karimtera]

That would be easier, I am on it.