Silence MSVC build alignment warnings

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235450 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/modules/HandleLLVMOptions.cmake

@@ -304,7 +304,15 @@ if( MSVC )
     -wd4611 # Suppress 'interaction between '_setjmp' and C++ object destruction is non-portable'
     -wd4805 # Suppress 'unsafe mix of type <type> and type <type> in operation'
     -wd4204 # Suppress 'nonstandard extension used : non-constant aggregate initializer'
-
+
+	# Idelly, we'd like this warning to be enabled, but MSVC 2013 doesn't
+	# support the 'aligned' attribute in the way that clang sources requires (for
+	# any code that uses the LLVM_ALIGNAS marco), so this is must be disabled to
+	# avoid unwanted alignment warnings.
+	# When we switch to requiring a version of MSVC that supports the 'alignas'
+	# specifier (MSVC 2015?) this warning can be re-enabled.
+    -wd4324 # Suppress 'structure was padded due to __declspec(align())'
+
     # Promoted warnings.
     -w14062 # Promote 'enumerator in switch of enum is not handled' to level 1 warning.