builtin_clang=OFF broken because of missing transitive dependencies

[hahnjo]

Since the upgrade to LLVM 16, building ROOT with builtin_clang=OFF fails to link. It can be "fixed" with the following diff:

diff --git a/interpreter/cling/lib/Interpreter/CMakeLists.txt b/interpreter/cling/lib/Interpreter/CMakeLists.txt
index e397da97f6..d0819c4667 100644
--- a/interpreter/cling/lib/Interpreter/CMakeLists.txt
+++ b/interpreter/cling/lib/Interpreter/CMakeLists.txt
@@ -14,13 +14,16 @@ set(LIBS
   clangParse
   clangSema
   clangAnalysis
+  clangASTMatchers
   clangEdit
   clangRewrite
   clangRewriteFrontend
   clangSerialization
+  clangAPINotes
   clangAST
   clangBasic
   clangLex
+  clangSupport
 )

 set(LLVM_LINK_COMPONENTS
@@ -29,6 +32,8 @@ set(LLVM_LINK_COMPONENTS
   coroutines
   coverage
   executionengine
+  FrontendDriver
+  FrontendHLSL
   ipo
   jitlink
   lto

However, this is incorrect because it just specifies the missing transitive dependencies. The proper fix is to correctly load ClangConfig.cmake which specifies the library targets and their dependencies.