SDL: Don't define memcpy(), memset() when using static VC runtime.

SDL Commits
1 
From 0e63b514d505116766c96a87ac8c5d614fe37cf1 Mon Sep 17 00:00:00 2001
From: Frank Richter <[EMAIL REDACTED]>
Date: Sat, 7 May 2022 14:52:35 +0200
Subject: [PATCH] Don't define memcpy(), memset() when using static VC runtime.

The linker will complain about duplicated symbols otherwise
(see #3662, #5156).
---
 src/stdlib/SDL_stdlib.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/stdlib/SDL_stdlib.c b/src/stdlib/SDL_stdlib.c
index 9d785aad563..62cbef884b3 100644
--- a/src/stdlib/SDL_stdlib.c
+++ b/src/stdlib/SDL_stdlib.c
@@ -549,8 +549,9 @@ int SDL_isblank(int x) { return ((x) == ' ') || ((x) == '\t'); }
 __declspec(selectany) int _fltused = 1;
 #endif
 
-/* The optimizer on Visual Studio 2005 and later generates memcpy() and memset() calls */
-#if _MSC_VER >= 1400
+/* The optimizer on Visual Studio 2005 and later generates memcpy() and memset() calls.
+   Always provide it for the SDL2 DLL, but skip it when building static lib w/ static runtime. */
+#if (_MSC_VER >= 1400) && (!defined(_MT) || defined(DLL_EXPORT))
 extern void *memcpy(void* dst, const void* src, size_t len);
 #pragma intrinsic(memcpy)
 
@@ -570,7 +571,7 @@ memset(void *dst, int c, size_t len)
 {
     return SDL_memset(dst, c, len);
 }
-#endif /* _MSC_VER >= 1400 */
+#endif /* (_MSC_VER >= 1400) && (!defined(_MT) || defined(DLL_EXPORT)) */
 
 #ifdef _M_IX86