added ispc directory, changed the dependencies scripts to use it during compilation

Former-commit-id: de7f13458968a1c7a296352929582b6994569366

tutorial/compile_dependencies_linux.sh

@@ -23,6 +23,7 @@ cd ../embree/
 rm -fr build
 mkdir build
 cd build
+cp ../ispc/ispc-v1.8.1-linux ispc
 cmake -DCMAKE_BUILD_TYPE=Release ../
 make
 

tutorial/compile_dependencies_macosx.sh

@@ -11,7 +11,8 @@ cd ../embree/
 rm -fr build
 mkdir build
 cd build
+cp ../ispc/ispc-v1.8.1-osx ispc
 cmake -DCMAKE_BUILD_TYPE=Release ../
-make
+make -j 16
 
 cd ../../../tutorial