Don't force /Zi when using CMAKE_MSVC_DEBUG_INFORMATION_FORMAT (microsoft#7041)

Newer versions of CMake have a more robust way of handling debug
information settings for Windows. Forcing this on breaks the ability to
control how debug info is generated and gets in the way of using
sccache.

See CMake's docs:

https://cmake.org/cmake/help/latest/variable/CMAKE_MSVC_DEBUG_INFORMATION_FORMAT.html

Author: llvm-beanz

cmake/modules/HandleLLVMOptions.cmake

@@ -357,9 +357,11 @@ if( MSVC )
 
   # Change release to always build debug information out-of-line, but
   # also enable Reference optimization, ie dead function elimination.
-  append("/Zi" CMAKE_CXX_FLAGS_RELEASE)
-  append("/DEBUG /OPT:REF" CMAKE_SHARED_LINKER_FLAGS_RELEASE)
-  append("/DEBUG /OPT:REF" CMAKE_EXE_LINKER_FLAGS_RELEASE)
+  if (NOT CMAKE_MSVC_DEBUG_INFORMATION_FORMAT)
+    append("/Zi" CMAKE_CXX_FLAGS_RELEASE)
+    append("/DEBUG /OPT:REF" CMAKE_SHARED_LINKER_FLAGS_RELEASE)
+    append("/DEBUG /OPT:REF" CMAKE_EXE_LINKER_FLAGS_RELEASE)
+  endif()
 
   # HLSL Changes End