Revert "[Syntax] Add minimal TableGen for syntax nodes. NFC"

This reverts commit 55120f7.

Segfaults during build:
http://lab.llvm.org:8011/#/builders/36/builds/1310

Author: sam-mccall

clang/include/clang/CMakeLists.txt

@@ -5,4 +5,3 @@ add_subdirectory(Parse)
 add_subdirectory(Sema)
 add_subdirectory(Serialization)
 add_subdirectory(StaticAnalyzer/Checkers)
-add_subdirectory(Tooling/Syntax)