Commit e214c44 (build: update ZiglingStep to the new API) broke again
the compatibility support for old compilers, due to the use of the
multi-object for loop syntax.
Move the Zig IPC support code to src/ipc.zig.
Use the while statement, instead of the for statement.
Update the code to the breaking change in ziglang commit
60eabc0ec (std.Build.CompileStep: remove run() and install())
Update the zig version in the README.md file.
The version check for Zig 0.6.0 was incorrect since commit
971ab7f (Use a zig build script to run ziglings).
Move compatibility support to a separate file, in order to simplify
build.zig.
In case of incompatible version, exit with code 3 instead of 0, in order
to detect the case of failure in a test (to be implemented).
Remove the use of comptime when checking compatibility at the start of
the build function, since it is not necessary.
Closes#210.
