Convert VTKLargeData test inputs to ExternalData content links

Add a Testing/Data directory with ExternalData content links mirroring
the content and layout we use from the VTKLargeData/Data directory.
Add a VTK_USE_LARGE_DATA option to enable tests using such data.

Call ExternalData_Expand_Arguments in */*/Testing/Cxx/CMakeLists.txt for
tests that reference these data files in order to tell the ExternalData
module to populate a ExternalData/Testing/Data directory in the build
tree.  Pass the ExternalData/Testing directory in the build tree as the
"-D" data directory option to tests using these data so that they can
find the files where ExternalData puts them at build time.

In the vtk_add_test_* API replace the LARGE_DATA options with a new
TESTING_DATA option to indicate that a test uses the directory
ExternalData/Testing/Data populated by ExternalData from the
Testing/Data source directory.

Drop VTK_LARGE_DATA_ROOT and stop using the VTKLargeData repository.
Drop references to VTKLargeData from test source comments.

Change-Id: Iaaf36293a840e65d6c171ae69b5c99db4c61443e
Fix compilation against libav 54 and OGG-Theora extension detection

Change-Id: I78892722d9294a43a8a6979c2ac4a6d39faf9378
Merge topic 'ogg-support' into master

4a67254c Fix compilation against libav 54 and OGG-Theora extension detection
Merge topic 'convert-VTKLargeData-to-ExternalData' into master

4fbc3a0d Convert VTKLargeData test inputs to ExternalData content links
Fix compilation against libav 54 and OGG-Theora extension detection

Change-Id: Id74688bcfeefae3c5904e0719d498a185930220e
Merge topic 'ogg-support-rel' into master

1967fef7 Fix compilation against libav 54 and OGG-Theora extension detection
ExternalData: Do not re-stage staged object files

The ExternalData_LINK_CONTENT option tells ExternalData to convert real
data files it finds into content links and to "stage" the original
content in a ".ExternalData_<algo>_<hash>" file.  However, after a data
object has been staged it is possible that a user-provided pattern in
the "REGEX:" option will later match the staged object file.  We must
not process staged object files even when a user pattern matches them.

Fix the implementation to not match a staged object file as a normal
data file for conversion.

Change-Id: Ie9340855e0b1af93bfeae284805339b8ee8e0295
Merge topic 'ExternalData-no-re-stage' into master

33d241e8 ExternalData: Do not re-stage staged object files
Update the scalar bar build time.

The BuildTime member is not being updated when the
scalar bar layout is recalculated, causing layouts
to be recomputed every time the bar is rendered.

Change-Id: I79615dfee885cf13b64370bd53dd6bc9485980cd
Merge topic '14095_scalar_bar_redraws' into master

118aa20a Update the scalar bar build time.