Add ImportC compiler to dmd

[Walter Bright]

On 5/16/2021 3:51 AM, Dibyendu Majumdar wrote:
> I think that if this feature is going to added, then it makes sense to ensure 
> that a test suite is present to prove its correctness. Users should not be 
> expected to pay for wrong implementation. Perhaps the MIR C test suite I 
> referred to earlier can be used to validate the implementation; I think it has 
> good coverage of standard C and the tests are also small.

The Mir suite does look usable and good. I'm a bit concerned about the license 
for it, as I'd like to install the test suite on github.