Audio: cover also the official Windows SDK from Creative in the checks.

src/Magnum/Audio/Audio.cpp

@@ -33,12 +33,9 @@ namespace Magnum { namespace Audio {
 
 /* Verify types */
 static_assert(std::is_same<ALubyte, UnsignedByte>::value, "ALubyte is not the same as UnsignedByte");
-/** @todo Why `ALbyte` is defined as `char` and not `signed char` on OSX? */
-#ifndef CORRADE_TARGET_APPLE
-static_assert(std::is_same<ALbyte, Byte>::value, "ALbyte is not the same as Byte");
-#else
-static_assert(std::is_signed<ALbyte>::value && sizeof(ALbyte) == 1, "ALbyte does not have the same characteristics as Byte");
-#endif
+/* ALbyte is defined as `signed char` in OpenAL Soft and `char` in the official
+   SDK from Creative and on Apple. Both are okay. */
+static_assert(std::is_same<ALbyte, Byte>::value || std::is_signed<ALbyte>::value && sizeof(ALbyte) == 1, "ALbyte does not have the characteristics as Byte");
 static_assert(std::is_same<ALushort, UnsignedShort>::value, "ALushort is not the same as UnsignedShort");
 static_assert(std::is_same<ALshort, Short>::value, "ALshort is not the same as Short");
 static_assert(std::is_same<ALuint, UnsignedInt>::value, "ALuint is not the same as UnsignedInt");