[REVIEW 3-6 (but only 3.6.2?)] No more prereg, no more unopkg sync

Quoting 
<http://cgit.freedesktop.org/libreoffice/core/commit/?id=6dcb3d4ef46312729bb6f16c473b433474863f68> 
"Related fdo#51252: No more prereg, no more unopkg sync":  "Now that 
5c47e5f63a79a9e72ec4a100786b1bbf65137ed4 'fdo#51252 Disable copying 
share/prereg/bundled to avoid startup crashes' removed the use of 
share/prereg, there is no longer need to generate it in the first place 
(by calling 'unopkg sync' at build or installation time), and so no need 
for the 'unopkg sync' sub-command, either.  This also allows to simplify 
some of the jvmfwk code that was only there so that 'unopkg sync' (which 
can require a JVM) can work in 'hostile' environments (during build and 
installation)."

This is a somewhat large patch, removing stuff all over the code base. 
I checked it on all of Linux, Mac OS X, and Windows, but might well have 
missed one or the other nuance, esp. in terra incognita like 
setup_native/source/win32/customactions.

Hence, I would suggest to not jeopardize LO 3.6.1 with this clean up, 
but only backport it to libreoffice-3-6 after branch-off of 
libreoffice-3-6-1 early next week.  (This clean up would nicely remove 
the root for <https://bugs.freedesktop.org/show_bug.cgi?id=44628> 
"unopkg.exe does not find VC runtime during install (extension 
registration)," but it might be better to address that with yet another 
targeted band-aid fix for LO 3.6.1, like by just not calling "unopkg 
sync" from the msi install scripts.)

Stephan