CMake: Generate SONAME attribute for shared objects

Previosuly, generation of the SONAME attribute was disabled.
This caused libraries to have relative paths in DT_NEEDED attributes
(e.g "Libraries/libcore.so" instead of just "libcore.so"),
which caused build errors when the working directory during build was
not $SERENITY_ROOT/Build.

This caused the build of ports that use libraries other than libc.so
to fail (e.g the nesalizer port).

Closes #4457

CMakeLists.txt

@@ -99,7 +99,6 @@ foreach(lang ASM C CXX OBJC OBJCXX)
     unset(CMAKE_SHARED_MODULE_LOADER_${lang}_FLAG )
     unset(CMAKE_${lang}_OSX_DEPLOYMENT_TARGET_FLAG)
     unset(CMAKE_${lang}_SYSROOT_FLAG)
-    unset(CMAKE_SHARED_LIBRARY_SONAME_${lang}_FLAG)
 endforeach()
 
 set(CMAKE_INSTALL_NAME_TOOL "true")