[clang] [CIR] Minimize dependencies of check-clang-cir (PR #227957)

[Mehdi Amini via cfe-commits]

================
@@ -238,11 +238,54 @@ add_lit_testsuite(check-clang "Running the Clang regression tests"
   ARGS ${CLANG_TEST_EXTRA_ARGS}
   )
 
+# Skip CIR here. check-clang above still runs these tests. The check-clang-cir
+# target is created explicitly below so that it (and its subdirectory-based
+# sub-targets) depend only on the tools those tests invoke and the tools
+# required to load clang/test/lit.cfg.py.
 add_lit_testsuites(CLANG ${CMAKE_CURRENT_SOURCE_DIR}
   DEPENDS ${CLANG_TEST_DEPS}
   FOLDER "Clang tests/Suites"
+  SKIP "^CIR"
 )
 
+# These tools are resolved while loading clang/test/lit.cfg.py, or invoked
+# directly by tests under clang/test/CIR.
+set(CLANG_CIR_TEST_DEPS
+  clang
+  )
+if(CLANG_ENABLE_CIR)
----------------
joker-eph wrote:

Looks like to me that this entire hunk should be guarded by `if(CLANG_ENABLE_CIR)`, including adding the lit targets.

https://github.com/llvm/llvm-project/pull/227957