Fixup install rules

Explicitly build and install the draco shared library _only_

CMakeLists.txt

@@ -608,7 +608,8 @@ ELSE()
         )
       ENDIF()
 
-      ADD_SUBDIRECTORY( "contrib/draco" )
+      # Don't build or install all of Draco by default
+      ADD_SUBDIRECTORY( "contrib/draco" EXCLUDE_FROM_ALL )
 
       if(MSVC OR WIN32)
         set(draco_LIBRARIES "draco")
@@ -626,6 +627,12 @@ ELSE()
         EXCLUDE_FROM_DEFAULT_BUILD TRUE
         )
 
+      # Do build the draco shared library
+      set_target_properties(${draco_LIBRARIES} PROPERTIES
+        EXCLUDE_FROM_ALL FALSE
+        EXCLUDE_FROM_DEFAULT_BUILD FALSE
+        )
+
       TARGET_USE_COMMON_OUTPUT_DIRECTORY(${draco_LIBRARIES})
       TARGET_USE_COMMON_OUTPUT_DIRECTORY(draco_encoder)
       TARGET_USE_COMMON_OUTPUT_DIRECTORY(draco_decoder)