Add ImportC compiler to dmd

[Chris Piker]

On Sunday, 16 May 2021 at 00:00:30 UTC, Walter Bright wrote:
> So, I propose that once ImportC is ready, that persons familiar 
> with those code bases try out the SQLite and Lua projects. 
> Failures should be reduced to minimal test cases for 
> incorporation into the ImportC test suite.

If you think it would be helpful I'll try building our in-house C
libraries since I understand those and submit any cases that fail.
I imagine quite a few people are going to be intrigued by this
project (as a new C compiler doesn't come around every day) and
will try building most of their C projects/dependencies.

I'm not sure if this is applicable, but we still have some sun/
sparc machines around in case building on a big endian environment
would provide you with useful data.  Sparc cores are still burned
into quite a few FPGAs.

The test suite should build up quickly.  Getting rid of duplicate
tests may turn out to be an issue.