Remove redundant(?) initialization of frame geometry

The memset of maGeometry was added with 79e2c257
"INTEGRATION: CWS vclplug" in 2003, before
f7be3916 "INTEGRATION: CWS presenterview" in
2008 introduced a user-provided _SalFrameGeometry default ctor, which sets all
members except nWidth and nHeight to 0, and sets nWidth and nHeight to 1.

So the memset effectively set nWidth and nHeight to back 0 (whether or not that
was by design or by accident after the latter commit), but that seems to be
unnecessary after all, seeing that a SAL_USE_VCLPLUGIN=gen soffice appears to
stll work well after removing the memset.

Change-Id: Ic6d1c6476a1234e84dca1e560149cd1e9af37b73
Reviewed-on: https://gerrit.libreoffice.org/48696Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

vcl/unx/generic/window/salframe.cxx

@@ -822,9 +822,6 @@ X11SalFrame::X11SalFrame( SalFrame *pParent, SalFrameStyleFlags nSalFrameStyle,
 {
     GenericUnixSalData *pData = GetGenericUnixSalData();
 
-    // initialize frame geometry
-    memset( &maGeometry, 0, sizeof(maGeometry) );
-
     mpParent                    = static_cast< X11SalFrame* >( pParent );
 
     mbTransientForRoot          = false;