Update SDL to Hg d7abc11bb69a

https://github.com/cgutman/moonlight-deps/commit/20ce1c15eddb0ee9b216b0928844412e3e63e1d6

libs/mac/Frameworks/SDL2.framework/Versions/A/Resources/Info.plist

@@ -3,7 +3,7 @@
 <plist version="1.0">
 <dict>
 	<key>BuildMachineOSBuild</key>
-	<string>19E287</string>
+	<string>19H114</string>
 	<key>CFBundleDevelopmentRegion</key>
 	<string>English</string>
 	<key>CFBundleExecutable</key>
@@ -19,7 +19,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>2.0.14</string>
+	<string>2.0.15</string>
 	<key>CFBundleSignature</key>
 	<string>SDLX</string>
 	<key>CFBundleSupportedPlatforms</key>
@@ -27,7 +27,7 @@
 		<string>MacOSX</string>
 	</array>
 	<key>CFBundleVersion</key>
-	<string>2.0.14</string>
+	<string>2.0.15</string>
 	<key>DTCompiler</key>
 	<string>com.apple.compilers.llvm.clang.1_0</string>
 	<key>DTPlatformBuild</key>

libs/mac/Frameworks/SDL2.framework/Versions/A/Resources/License.txt

@@ -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