Fix symbol export/visibility

Turns out that this macro is needed also on Mac OS X builds (both with
GCC 11.3 for x86_64 and with Apple clang version 14.0.0
(clang-1400.0.29.202) for arm64-apple-darwin22.1.0). If I'm reading my
original commit message correctly, this was only choking on MSVC, so
let's use that macro everywhere but on MSVC.

Fixes: 1d7c822 Make this buildable on Ubuntu 20.04 with GCC 10
Bug: #7
Change-Id: Ib3502057d17ab8d4a138de02204d0b8e1e1c6442

include/libyang-cpp/Enum.hpp

@@ -292,12 +292,12 @@ constexpr ParseOptions operator|(const ParseOptions a, const ParseOptions b)
 }
 
 std::ostream& operator<<(std::ostream& os, const NodeType& type)
-#if defined(__GNUC__) && !defined(__llvm__) && __GNUC__ <= 10
+#if !defined(_MSC_VER)
     LIBYANG_CPP_EXPORT
 #endif
     ;
 std::ostream& operator<<(std::ostream& os, const ErrorCode& err)
-#if defined(__GNUC__) && !defined(__llvm__) && __GNUC__ <= 10
+#if !defined(_MSC_VER)
     LIBYANG_CPP_EXPORT
 #endif
     ;