SDK: Add libcapstone-dev
We already have libcapstone3 in the SDK as a side-effect of including libcasefold-dev, and Proton wants its development headers too. With current information we believe it gets linked statically and so is not needed in the Platform.
Resolves: #8 (closed)
SDK: Add libxpresent-dev
We added libXpresent.so.1 to the Platform a while ago, but didn't add its development headers to the SDK. Proton needs them.
SDK: Add gcc build-dependencies
The Proton SDK Docker image, which is used to build Proton, needs to build a newer gcc cross-compiler targeting the Windows ABI (currently using mingw-w64). We already have runtime libraries corresponding to these; if we add their development files, that's one less thing for the Proton SDK to arrange.
Resolves: #10 (closed)
Part of internal task T28539. I need to test this to make sure it doesn't pull in anything unexpected, but I think it should be relatively straightforward.