fix Issue 23548 - [REG 2.098] C sources files have precedent over D modules in imports

[ibuclaw]

Restores import behaviour to pre-2.098. ImportC is not part of the language, it's an add-on, and shouldn't hijack the importing of D modules.

Other choices include:

• Do the same as we have for import("foo.c"), and have a specific list of include paths only searched for .c, .h, and .i files.
• Change syntax to import(C) foo; so there can be no ambiguity in the language.
• Likewise, but use import "foo.h".
• MixinC: http://dpldocs.info/experimental-docs/mixinc.html

[dlang-bot]

Thanks for your pull request, @ibuclaw!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	23548	regression	[REG 2.098] C sources files have precedent over D modules in imports

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#14700"

[ibuclaw]

oh no not again #14692 #14687