[clang] [cmake] Fix gen_ast_dump_json_test.py binary dir

[mgorny]

Summary

Use correct directory to put gen_ast_dump_json_test.py instead of
LLVM_BINARY_DIR. This fixes attempting to write to /usr when building
clang standalone.

[arichardson]

LGTM

clang/test/CMakeLists.txt

list(APPEND CLANG_TEST_DEPS
       CheckerDependencyHandlingAnalyzerPlugin
       CheckerOptionHandlingAnalyzerPlugin
       )
   endif()
 endif()
 
 # Copy gen_ast_dump_json_test.py to the clang build dir. This allows invoking
 # it without having to pass the --clang= argument
-configure_file(AST/gen_ast_dump_json_test.py ${LLVM_TOOLS_BINARY_DIR}/gen_ast_dump_json_test.py COPYONLY)
+configure_file(AST/gen_ast_dump_json_test.py
+  ${CLANG_BINARY_DIR}/bin/gen_ast_dump_json_test.py COPYONLY)
 
 add_custom_target(clang-test-depends DEPENDS ${CLANG_TEST_DEPS})
 set_target_properties(clang-test-depends PROPERTIES FOLDER "Clang tests")
 
 add_lit_testsuite(check-clang "Running the Clang regression tests"
   ${CMAKE_CURRENT_BINARY_DIR}
   #LIT ${LLVM_LIT}
   PARAMS ${CLANG_TEST_PARAMS}