Avoid some warnings when compiling the test with Visual C++.

[SVN r40004]

test/hash_float_test.hpp

@@ -17,6 +17,10 @@
 #include <boost/limits.hpp>
 
 #include <iostream>
+#if defined(BOOST_MSVC)
+#pragma warning(push)
+#pragma warning(disable:4127) // conditional expression is constant
+#endif
 
 template <class T>
 void float_tests(char const* name, T* = 0)
@@ -198,3 +202,6 @@ void float_tests(char const* name, T* = 0)
 #endif
 }
 
+#if defined(BOOST_MSVC)
+#pragma warning(pop)
+#endif