[clang] NFC: Make clang resource headers an interface library (PR #88317)

[Saleem Abdulrasool via cfe-commits]

================
@@ -501,6 +501,10 @@ add_header_target("windows-resource-headers" ${windows_only_files})
 add_header_target("utility-resource-headers" ${utility_files})
 
 get_clang_resource_dir(header_install_dir SUBDIR include)
+target_include_directories(clang-resource-headers INTERFACE
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
----------------
compnerd wrote:

Do we need to worry about other files accidentally being made visible by using the source directory?

https://github.com/llvm/llvm-project/pull/88317