This reverts commit dc825fc4.

* Centralise the generation of help for root command

Add argparse2help.py, add root-argparse.py, delete the old help of root, add the cmake commands needed to generate the header containing the command line options help and to generate manual page for the root command.

The python file argparse2help.py can be called with the root-argparse.py and the output name as arguments. This call will generate the header file if the output has an extension ".h" and will generate the manual page if the extension is ".1"

* Centralise the generation of help for the rest of the commands

Add cmake changes to generate headers and manual pages for rootcling hadd and hist2workspace
Delete old man pages of hadd and hist2workspace
Add commented out generation of man pages for python commands, we need to add a dependency before uncommenting them out
Add hadd rootcling hist2workspace argparse modules

* make the path compatible with windows

* review modifications

* add dependency on the input and the generation script of man pages

* remove installation of headers

* Update CMakeLists.txt

It makes no sense to generates man pages on Windows. Windows does not have the `man` command.

* Update argparse2help.py

* Update argparse2help.py

* Update argparse2help.py

* Update hadd.cxx

haddCommandLineOptionsHelp.h was not included for windows

* Update root-argparse.py

add the option --version

* Update argparse2help.py

simplified version (Thanks Bertrand !)

in ROOT6 there is only one kind of reflection information. For this
reason, also the neighbouring references to Reflex have been removed.

this is done until the present ABI issues between gcc and clang are
solved, most notably the ones concerning shared_ptrs.

* modified python files to be able to be called by argparse2help.py

* modified argparse2help to handle options with no help

* stop the scripts from running when imported

* [man,help] Add script to generate man, .h page. Use for `root`.

* Script improvements

* fix path bug

* bug fix

(cherry picked from commit 4a06e1b1c0d3da7f604f277c7dd27ed25ed8f8f1)

valarray triggers lots of symbols to be emitted during startup.

This reverts commit 86ffaecb.

This breaks runtime_cxxmodules.

This reverts commit 95812645.

This breaks the runtime_cxxmodules.

Add back the stdlib module in libc, move sys/types.h, too.

This patch should resolve a recently introduced include cycle.

ROOT needs an overlay files in the include directory during runtime
to correctly mount the system modulemaps for libc/STL. For this
we need to generate and install a new overlay file that points to
the *installed* modulemaps for those libraries.

We can't use the existing modulemap as this one still points to the
original build directory.

We also need to install the related stl/lib modulemaps.

This reduces the duplications in all modules reducing the overall
modules size by 1MB.

ACLiC needs to produce position independent code for its objects,
or it will fail at runtime.

Don't copy the clang headers, which can conflict with the system headers, like for example "future" which can now be put back in the pch headers list

There are three different kinds of header files in Core:
  * C headers - they can be included in C contexts
  * Config headers - they are supposed to be textually included in each
    TU.
  * No RTTI C++ headers - they can be built in non-rtti context which is
    needed for stage1 builds.

The rest of the headers in Core require rtti in order to be built, either
because they use typeinfo or exceptions.

This patch structures the ROOT's special modules in that way allowing
implicit module builds to be trigger from the right complation. For
example, we cannot (and should not) trigger build of C++ module when
compiling C code.

rootcling should never implicitly build a module that is associated
with a ROOT dict as such a module needs the rootcling transformations
(e.g. to preserve the source code comments for class member as
annotated attributes). The only implicitly built modules should be
system libraries that don't need those transformations.

To inform the user that this shouldn't happen we add a new clang
diagnostic client that listens for the -Rmodule-build remarks and
verifies that every module built this way is a system module.

The reason for choosing a diag client is that clang is building
those modules in a very isolated environment that doesn't leak any
other information out that we could use to diagnose this. The only
supported way clang is informing clients about implicit module builds
seems to be the -Rmodule-build remarks.

This reverts commit a827a4fa.

This reverts commit 0f4f04f2.

Use os.path.normpath to make sure we use the correct os path (fixes the generation of allHeaders.h on Windows)