[NFC] Rename _LIBCPP_TYPE_VIS_ONLY to _LIBCPP_TEMPLATE_VIS

The name _LIBCPP_TYPE_VIS_ONLY is no longer accurate because both
_LIBCPP_TYPE_VIS and _LIBCPP_TYPE_VIS_ONLY expand to
__attribute__((__type_visibility__)) with Clang. The only remaining difference
is that _LIBCPP_TYPE_VIS_ONLY can be applied to templates whereas
_LIBCPP_TYPE_VIS cannot (due to dllimport/dllexport not being allowed on
templates).

This patch renames _LIBCPP_TYPE_VIS_ONLY to _LIBCPP_TEMPLATE_VIS.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@291035 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/mutex b/include/mutex
index 79befbe..155b2c3 100644
--- a/include/mutex
+++ b/include/mutex
@@ -465,7 +465,7 @@
 
 #endif // !_LIBCPP_HAS_NO_THREADS
 
-struct _LIBCPP_TYPE_VIS_ONLY once_flag;
+struct _LIBCPP_TEMPLATE_VIS once_flag;
 
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
@@ -485,7 +485,7 @@
 
 #endif  // _LIBCPP_HAS_NO_VARIADICS
 
-struct _LIBCPP_TYPE_VIS_ONLY once_flag
+struct _LIBCPP_TEMPLATE_VIS once_flag
 {
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR
@@ -615,7 +615,7 @@
 #if defined(_LIBCPP_ABI_VARIADIC_LOCK_GUARD) \
     && !defined(_LIBCPP_CXX03_LANG)
 template <>
-class _LIBCPP_TYPE_VIS_ONLY lock_guard<> {
+class _LIBCPP_TEMPLATE_VIS lock_guard<> {
 public:
     explicit lock_guard() {}
     ~lock_guard() = default;
@@ -628,7 +628,7 @@
 };
 
 template <class ..._MArgs>
-class _LIBCPP_TYPE_VIS_ONLY lock_guard
+class _LIBCPP_TEMPLATE_VIS lock_guard
 {
     static_assert(sizeof...(_MArgs) >= 2, "At least 2 lock types required");
     typedef tuple<_MArgs&...> _MutexTuple;