scripts: osx: fix path to SDL2 framework

scripts/build_osx_engine.sh

@@ -9,7 +9,7 @@ export CC="/usr/bin/clang"
 export CXX="/usr/bin/clang++"
 export CFLAGS="-m32"
 export CXXFLAGS="-m32"
-python waf configure --sdl2=~/Library/Frameworks/SDL2.framework/ --vgui=$TRAVIS_BUILD_DIR/vgui-dev --build-type=debug || die
+python waf configure --sdl2=$HOME/Library/Frameworks/SDL2.framework/ --vgui=$TRAVIS_BUILD_DIR/vgui-dev --build-type=debug || die
 python waf build -j2 || die
 # mkdir -p pkg/
 # cp engine/libxash.dylib game_launch/xash3d mainui/libxashmenu.dylib vgui_support/libvgui_support.dylib VGUI/vgui-dev-master/lib/vgui.dylib ../scripts/xash3d.sh # pkg/