[libc++] Merge _LIBCPP_FUNC_VIS, _LIBCPP_TYPE_VIS and _LIBCPP_EXCEPTION_ABI into _LIBCPP_EXPORTED_FROM_ABI

These macros are always defined identically, so we can simplify the code a bit by merging them.

Reviewed By: ldionne, #libc

Spies: libcxx-commits, krytarowski, smeenai

Differential Revision: https://reviews.llvm.org/D152652
diff --git a/libcxx/src/valarray.cpp b/libcxx/src/valarray.cpp
index 5d63bc1..f377e0f 100644
--- a/libcxx/src/valarray.cpp
+++ b/libcxx/src/valarray.cpp
@@ -12,8 +12,8 @@
 
 // These two symbols are part of the v1 ABI but not part of the >=v2 ABI.
 #if _LIBCPP_ABI_VERSION == 1
-template _LIBCPP_FUNC_VIS valarray<size_t>::valarray(size_t);
-template _LIBCPP_FUNC_VIS valarray<size_t>::~valarray();
+template _LIBCPP_EXPORTED_FROM_ABI valarray<size_t>::valarray(size_t);
+template _LIBCPP_EXPORTED_FROM_ABI valarray<size_t>::~valarray();
 #endif
 
 template void valarray<size_t>::resize(size_t, size_t);