Update SDL to version 2.0.14.

libs/SDL2/.hgignore

@@ -4,13 +4,34 @@ autom4te*
 config.cache
 config.log
 config.status
+libtool
 Makefile
-sdl-config
+Makefile.rules
+sdl2-config
+sdl2-config.cmake
+sdl2.pc
 SDL2.spec
 build
 gen
 Build
 
+# for CMake
+CMakeFiles/
+CMakeCache.txt
+cmake_install.cmake
+cmake_uninstall.cmake
+SDL2ConfigVersion.cmake
+*.a
+*.la
+*.so
+*.so.*
+.ninja_*
+*.ninja
+
+# for CLion
+.idea
+cmake-build-*
+
 # for Xcode
 *.orig
 *.swp
@@ -58,7 +79,7 @@ VisualC/visualtest/testsprite2_sample.parameters
 # for Android
 android-project/local.properties
 
-sdl.pc
+test/aclocal.m4
 test/autom4te*
 test/config.cache
 test/config.log
@@ -122,10 +143,13 @@ test/testthread
 test/testtimer
 test/testver
 test/testviewport
+test/testvulkan
 test/testwm2
 test/testyuv
 test/torturethread
 test/*.exe
+test/*,e1f
+test/*,ff8
 test/*.dSYM
 buildbot
 test/buildbot