Rendering/Parallel: export and install `vtkCompositeZPassFS`

Used within ParaView.

Documentation/release/dev/shader-symbol-exports.md

@@ -5,3 +5,4 @@ only those that are available through installed headers are available. These
 include:
 
 - `vtkTextureObjectVS` from `VTK::RenderingOpenGL2`
+- `vtkCompositeZPassFS` from `VTK::RenderingParallel`

Rendering/Parallel/CMakeLists.txt

@@ -15,12 +15,22 @@ set(classes
   vtkTreeCompositer)
 
 set(shader_files
-  vtkCompositeZPassShader_fs.glsl
+  vtkCompositeZPassShader_fs.glsl)
+set(public_shader_files
   vtkCompositeZPassFS.glsl)
 
 set(sources)
 set(private_headers)
 foreach (shader_file IN LISTS shader_files)
+  vtk_encode_string(
+    INPUT         "${shader_file}"
+    HEADER_OUTPUT header
+    SOURCE_OUTPUT source)
+  list(APPEND sources ${source})
+  list(APPEND private_headers ${header})
+endforeach ()
+set(headers)
+foreach (shader_file IN LISTS public_shader_files)
   vtk_encode_string(
     INPUT         "${shader_file}"
     EXPORT_SYMBOL "VTKRENDERINGPARALLEL_EXPORT"
@@ -28,12 +38,13 @@ foreach (shader_file IN LISTS shader_files)
     HEADER_OUTPUT header
     SOURCE_OUTPUT source)
   list(APPEND sources ${source})
-  list(APPEND private_headers ${header})
+  list(APPEND headers ${header})
 endforeach ()
 
 vtk_module_add_module(VTK::RenderingParallel
   CLASSES ${classes}
   SOURCES ${sources}
+  HEADERS ${headers}
   PRIVATE_HEADERS ${private_headers})
 
 vtk_module_definitions(VTK::RenderingParallel