Perf: MSVC driver should not consider unknown arguments as file names

Reading of build-wrapper-dump.json might be slow on Windows with MSVC. Symptom of this - is empty lines in analysis log as shown below:

INFO: Using build-wrapper output: D:\compilation-database\build-wrapper-dump.json
INFO:
INFO:
INFO: 0 compilation units analyzed, current is D:\project\example.cpp

And negative impact is even bigger in case of multi-module configurations that do not utilize CPP-1773 i.e. LTS <= SQ < 6.4.

This is caused by a slow processing of command-line option /AI. The whole argument such as /AIC: is considered as filename and such name is invalid - https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx

Performance degradation in this case is a regression introduced by CPP-850.

We should not consider arguments that start with minus and slash as filenames:

cl : Command line warning D9002 : ignoring unknown option '/hello.c'
cl : Command line error D8003 : missing source filename

Note that cl \hello.c works.

Conversion of minus into slash was added in CPP-1330, but for completeness of test here:

1 file(s) moved.

cl : Command line warning D9002 : ignoring unknown option '-hello.c'
cl : Command line error D8003 : missing source filename