LibVideo: Remove headers from CMakeLists.txt

Author: https://github.com/Zaggy1024
Commit: caee37ef9c
Pull-request: https://github.com/SerenityOS/serenity/pull/15363
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/FireFox317
Reviewed-by: https://github.com/MacDue
Reviewed-by: https://github.com/davidot

Userland/Libraries/LibVideo/CMakeLists.txt

@@ -1,14 +1,10 @@
 set(SOURCES
-    MatroskaDocument.h
     MatroskaReader.cpp
     VP9/BitStream.cpp
     VP9/Decoder.cpp
-    VP9/Enums.h
-    VP9/LookupTables.h
     VP9/MV.cpp
     VP9/Parser.cpp
     VP9/ProbabilityTables.cpp
-    VP9/Symbols.h
     VP9/SyntaxElementCounter.cpp
     VP9/TreeParser.cpp
     VP9/Utilities.cpp