UB2 now signs and notarizes, upgraded to SDL 2.0.16

Also works on Apple Silicon. Specific signing values are in a non-committed file, and the ub2 script only notarizes if a "notarize" flag is passed in on the command line.

NOTE: the SDL dylib currently only has x86_64 and arm64, will need extra work to graft those back in and keep the Notary service happy.

code/SDL2/include/SDL_config_macosx.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -115,8 +115,12 @@
 #define HAVE_LOGF   1
 #define HAVE_LOG10  1
 #define HAVE_LOG10F 1
+#define HAVE_LROUND 1
+#define HAVE_LROUNDF 1
 #define HAVE_POW    1
 #define HAVE_POWF   1
+#define HAVE_ROUND 1
+#define HAVE_ROUNDF 1
 #define HAVE_SCALBN 1
 #define HAVE_SCALBNF    1
 #define HAVE_SIN    1
@@ -133,6 +137,12 @@
 #define HAVE_SYSCONF    1
 #define HAVE_SYSCTLBYNAME 1
 
+#if defined(__has_include) && (defined(__i386__) || defined(__x86_64))
+# if __has_include(<immintrin.h>)
+#   define HAVE_IMMINTRIN_H 1
+# endif
+#endif
+
 #define HAVE_GCC_ATOMICS 1
 
 /* Enable various audio drivers */