[libcxx] [test] Suppress MSVC's /analyze warning C6294 in a more fine-grained manner.

Fixes D32926.

llvm-svn: 302325
diff --git a/libcxx/test/std/utilities/template.bitset/bitset.members/test.pass.cpp b/libcxx/test/std/utilities/template.bitset/bitset.members/test.pass.cpp
index 1a2d706..084dc9f8 100644
--- a/libcxx/test/std/utilities/template.bitset/bitset.members/test.pass.cpp
+++ b/libcxx/test/std/utilities/template.bitset/bitset.members/test.pass.cpp
@@ -15,6 +15,10 @@
 
 #include "test_macros.h"
 
+#if defined(TEST_COMPILER_C1XX)
+#pragma warning(disable: 6294) // Ill-defined for-loop:  initial condition does not satisfy test.  Loop body not executed.
+#endif
+
 template <std::size_t N>
 std::bitset<N>
 make_bitset()