Upgrade SDL2 to v. 2.0.14

source/include/begin_code.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2019 Sam Lantinga <[email protected]>
+  Copyright (C) 1997-2020 Sam Lantinga <[email protected]>
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -51,15 +51,11 @@
 
 /* Some compilers use a special export keyword */
 #ifndef DECLSPEC
-# if defined(__WIN32__) || defined(__WINRT__)
-#  ifdef __BORLANDC__
-#   ifdef BUILD_SDL
-#    define DECLSPEC
-#   else
-#    define DECLSPEC    __declspec(dllimport)
-#   endif
-#  else
+# if defined(__WIN32__) || defined(__WINRT__) || defined(__CYGWIN__)
+#  ifdef DLL_EXPORT
 #   define DECLSPEC __declspec(dllexport)
+#  else
+#   define DECLSPEC
 #  endif
 # elif defined(__OS2__)
 #   ifdef BUILD_SDL