[clang-tidy] Reduce the dependencies for the "make-confusable-table" tool

[mstorsjo]

Summary

When cross compiling llvm, a separate recursive native cmake build
is generated, for building the tools that generate code (unless they're
provided externally by the caller).

This reduces the number of build steps for that native build from
1000+ steps to 162.

This matches how the clang-pseudo-gen tool is set up in
clang-tools-extra/pseudo/gen/CMakeLists.txt.

[sammccall]

This matches what I did for clang-pseudo-gen. It looks reasonable to me, but I'd love to get a third opinion...
(If none in a couple of days, happy to stamp it)

[serge-sans-paille]

I'm fine with this too.

clang-tools-extra/clang-tidy/misc/ConfusableTable/CMakeLists.txt

+set(LLVM_LINK_COMPONENTS Support)
+list(REMOVE_ITEM LLVM_COMMON_DEPENDS clang-tablegen-targets)
+
 add_llvm_executable(make-confusable-table
   BuildConfusableTable.cpp
   )