Add BUILD_SHARED_LIBS build option to ROOT
Add BUILD_SHARED_LIBS build option to ROOT

The variable BUILD_SHARED_LIBS is treated specially by CMake, as
described below:

$ cmake --help-variable BUILD_SHARED_LIBS
BUILD_SHARED_LIBS
-----------------

Global flag to cause ``add_library()`` to create shared libraries if on.

If present and true, this will cause all libraries to be built shared
unless the library was explicitly added as a static library.  This
variable is often added to projects as an ``option()`` so that each user
of a project can decide if they want to build the project using shared or
static libraries.

karies/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,karies/root,karies/root,olifre/root,olifre/root,karies/root,olifre/root,olifre/root,root-mirror/root,karies/root,karies/root,karies/root,karies/root,root-mirror/root,olifre/root,karies/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root