Re-enable MSVC C5105 diagnostic; NFC (#182524)

From MSDN:

https://learn.microsoft.com/en-us/cpp/error-messages/compiler-warnings/c5105?view=msvc-170

> macro expansion producing 'defined' has undefined behavior

This diagnostic was disabled in 9a708855daeb6f70bbde7c2bc63e061ebaf072df
due to it triggering in system headers like WinBase.h. From my local
testing, the issue seems to have either been resolved in the system
headers or in MSVC, because enabling the warning does not trigger any
diagnostics for me.

llvm/cmake/modules/HandleLLVMOptions.cmake

diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index 7507b5f..104c52a 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -765,10 +765,6 @@
       -wd4592 # Suppress ''var': symbol will be dynamically initialized (implementation limitation)
       -wd4319 # Suppress ''operator' : zero extending 'type' to 'type' of greater size'
 
-      # We'd like this warning to be enabled, but it triggers from code in
-      # WinBase.h that we don't have control over.
-      -wd5105 # Suppress macro expansion producing 'defined' has undefined behavior
-
       # Ideally, we'd like this warning to be enabled, but even MSVC 2019 doesn't
       # support the 'aligned' attribute in the way that clang sources requires (for
       # any code that uses the LLVM_ALIGNAS macro), so this is must be disabled to