Minimal iOS build

[gavv]

Last revised: Oct 2023

In this issue we want to create a minimal iOS port and make it at least successfully building using scons.

Please see #292 to see how to run the minimal build and for details on the porting process. Just like with Windows, we'll have to implement a few iOS-specific components or at least add dummy implementations.

Note that we want to build Roc for iOS without creating Xcode project. We want to use our regular scons build. Thus we should teach it to work with iOS clang toolchain.

On the Internet there are some examples of building iOS libraries without Xcode, e.g. using a simple Makefile. We can start with specifying necessary compiler and linker flags using environment variables like CXXFLAGS and LDFLAGS. Later we'll integrate all necessary stuff into our scons scripts.

Related documentation:

• https://roc-streaming.org/toolkit/docs/building/scons_options.html
• https://roc-streaming.org/toolkit/docs/building/developer_cookbook.html
• https://roc-streaming.org/toolkit/docs/portability/cross_compiling.html
• https://roc-streaming.org/toolkit/docs/internals/code_structure.html#targets