Gui update timing report

[openroad-robot]

No description provided.

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[oharboe]

Tried it. Works.

$ make gui_floorplan
ODB_FILE=./results/nangate45/gcd/base/2_floorplan.odb GUI_SHOW=1 /home/oyvind/OpenROAD-flow-scripts/tools/install/OpenROAD/bin/openroad -gui  -minimize /home/oyvind/OpenROAD-flow-scripts/flow/scripts/open.tcl
QSocketNotifier: Can only be used with threads started with QThread
OpenROAD v2.0-17492-g8b46df0be 
Features included (+) or not (-): +Charts +GPU +GUI +Python
This program is licensed under the BSD-3 license. See the LICENSE file for details.
Components of this program may be licensed under more restrictive licenses which must be honored.
GUI_TIMING=1 reading timing, takes a little while for large designs...
Populating timing paths...OK
Prerendering...
instance _486_ is NONE
Skipping Placement heatmap, not all instances are placed
Skipping Routing heatmap, no routes available
Skipping RUDY heatmap, not all instances are placed
Dumping Power heatmap...
gui::select_chart "Endpoint Slack"
gui::update_timing_report 
gui::unminimize