libcxx: Stop using private MSVC macros in the exception implementation.

Inline the provided "fallback" definitions (which seem to always be
taken) that expand to __cdecl into users. The fallback definitions
for the *CRTIMP* macros were wrong in the case where the CRT is being
linked statically, so define our own macro as a replacement.

Differential Revision: https://reviews.llvm.org/D42158

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@322617 91177308-0d34-0410-b5e6-96231b3b80d8

include/__config

diff --git a/include/__config b/include/__config
index 94832ff..aa06452 100644
--- a/include/__config
+++ b/include/__config
@@ -626,6 +626,12 @@
 #endif // _LIBCPP_COMPILER_[CLANG|GCC|MSVC|IBM]
 
 #if defined(_LIBCPP_OBJECT_FORMAT_COFF)
+#ifdef _DLL
+# define _LIBCPP_CRT_FUNC __declspec(dllimport)
+#else
+# define _LIBCPP_CRT_FUNC
+#endif
+
 #if defined(_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS)
 # define _LIBCPP_DLL_VIS
 # define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS