Part XIX
Module
formula and fpicker

Part XVII
Module
fileaccess and filter

first commit to remove the broken xml filter source
view and validation service. The validation service
is currently broken in that it doesn't allow to refer
to or define an xml catalog or alternative validation
methods. All of this is included in current xml development
tools elsewhere, so we don't need to duplicate that in LO.

need to wait for reader thread to terminate before
deleting it.

should be pretty safe.
The main risk if is something rely on the 'undef if empty' behavior of
the typical trap is the use of *= in dmake
a git grep of "\$(SYSTEM_" did not reveal any problematic case.

This introduce config_host.mk and config_build.mk
generated from config_host.mk.in
The intent is for that file to be both sourcable in a shell and includable
in a gnu Makefile.
Eventually all the environment set-up will be in config_host.mk.in
and so there won't be a need to source anything in shell before make.

Pointers deleted in destructor are modified in remaining code,
and already set to NULL when necessary.

At least I suppose memory corruption is not intended behavior .-)