Add versioning support and update CMake configuration

[lum1n0us]

No description provided.

[lum1n0us]

@jirutka Please inform me if platforms other than Linux require the SONAME feature.

[jirutka]

The same applies to all Unix and Unix-like systems, so also BSDs and macOS.

[yamt]

maybe you can do it for all platforms and let cmake do whatever appropriate?
https://cmake.org/cmake/help/latest/prop_tgt/SOVERSION.html

[yamt]

build-tested for macOS.

master:

libiwasm.dylib:
        @rpath/libiwasm.dylib (compatibility version 0.0.0, current version 0.0.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1351.0.0)

with this PR:

libiwasm.dylib:
        @rpath/libiwasm.2.dylib (compatibility version 2.0.0, current version 2.2.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1351.0.0)

iirc, on macOS, a dylib can be loaded if

• the filename matches
• and compatibility version is larger than requested

[yamt]

looks reasonable to me

[yamt]

can you document the procedure?
eg. 1. update version.cmake, 2. run something (what?) to regen this file, 3. commit this generated file as well.