do not call LayoutEngine::reset()

Calling reset() disposes everything the LayoutEngine knows in its
current state. While this may have prevented some obscure crash during
exit in the past (call was added 2003-03-27), it definitely leads to a
crash if the updated LayoutEngine "patch"
http://download.icu-project.org/files/icu4c/51.1/icu-51-layout-fix-10107.tgz
is applied as that sets fGlyphStorage=NULL (it doesn't delete
LEGlyphStorage though and thus may leak, but that patch is in the wild
now) and a later call to mpIcuLE->layoutChars() tries to access
fGlyphStorage->...() if mpIcuLE is reused.

For the patch mentioned see
http://site.icu-project.org/download/51#TOC-Known-Issues and
http://bugs.icu-project.org/trac/ticket/10107

Change-Id: I1b8f5c446c174d7d12b896b3ecd2a266645e8abc
(cherry picked from commit 7de7267f)

implemented IcuFontFromServerFont::getFontTable(LETag,size_t&)

so that ICU versions trying to call
LEFontInstance::getFontTable(LETag,size_t&) actually call it instead of
IcuFontFromServerFont::getFontTable(LETag)

See http://site.icu-project.org/download/51#TOC-Known-Issues
"NOTE: Applications must implement LEFontInstance::getFontTable(LETag,
size_t &length)  in their LEFontInstance subclasses, so that ICU can
properly bounds-check font tables."

See also https://ssl.icu-project.org/trac/ticket/10107

(cherry picked from commit 428bde35)

Conflicts:
	vcl/generic/glyphs/gcach_layout.cxx

Change-Id: Ic20b7e8dda4e84734eb6de0ccba82b0dea481d55
Reviewed-on: https://gerrit.libreoffice.org/3755Reviewed-by: Miklos Vajna <vmiklos@suse.cz>
Tested-by: Miklos Vajna <vmiklos@suse.cz>