Previously it would retun the parent directory in case where a sub-directory creation was requested.

See https://root-forum.cern.ch/t/subdirectories/15665/11.

These includes may be used in dictionaries and therefore should
be available already in core libs

This patch also instruct the build system to not copy {libc,std}.modulemap in
OSX because the standard libraries are already modularized.

Fixes a regression introduced by root-project/root@603a1c3e96

rootcling writes dependency information which is never read/used when
loading the rdict file.

Let use this enum in win32gdk to avoid direct dependency from
Gui library there

This allows to deprecate the op= instead of any use of fgMaxSlot.
The latter is impossible as TThreadedObject needs to use it itself,
inside an inline (template member) function.

Use TNumSlots ctor to pass number of slots.
IMT use can still use the non-TNumSlots ctor; it will warn if IMT is off.

It is ambiguous whether TThreadedObject should rely on IMT, or whether it is used by user scheduling.
The default of 64 threads was good enough for user scheduling - unless the user needs more threads.
The default of 64 threads is also good enough for IMT, when IMT was not yet enabled - unless IMT ends up using more slots.
Thus, the silent default value is often misleading, and setting it through a static before construction is not exactly cplusplusy.

Instead, plovide a constructor tag that passed the number of slots - or "IMT" if that is what is wanted.
Add a warning if IMT is assumed but IMT is off, rather than failing, if IMT later needs more than fgMaxSlots slots.

Removing TClingRuntime.h, string.h, stddef.h, and stdlib.h.

Raise a warning if requesting a specific number of threads but the pool
has already been initialized with a different number.

Custom type name can be used in the future for identifying I/O
constructors

Separate methods used for dictionary generation and for 
creating of I/O constructor wrapper for templated classes

Avoid cling warning when generate code 

To keep support as requested in ROOT-7723

When non-default constructor is used, one cannot directly allocate array
of such objects. Therefore first allocate memory (arena) for them and
then call constructor with preallocated memory

Causes failing of roottest io_alloc and io_newdelete

Special case when default constructor not available.
Requires correspondent function generation

Need to use it when generate wrapper

Since 08e767cb, no llvm symbols are exported, and thus
none are subject to relocation, and thus existing llvm
symbols do not affect libCling and there is not need to
complain about existing llvm symbols.

Fix ROOT-9966.