Update the example opts files with symlink to sources

overview/debug.opts

@@ -4,4 +4,5 @@ CMAKE_FLAGS="
 -DCMAKE_CXX_COMPILER='/usr/bin/g++'
 -DCMAKE_CXX_FLAGS_DEBUG='-O0 -ggdb -Wall'
 -DCMAKE_BUILD_TYPE=Debug
+-DDUNE_SYMLINK_TO_SOURCE_TREE=1
 "

overview/release.opts

@@ -4,4 +4,5 @@ CMAKE_FLAGS="
 -DCMAKE_CXX_COMPILER='/usr/bin/g++'
 -DCMAKE_CXX_FLAGS_RELEASE='-O3 -DNDEBUG -g0 -Wno-deprecated-declarations -funroll-loops'
 -DCMAKE_BUILD_TYPE=Release
+-DDUNE_SYMLINK_TO_SOURCE_TREE=1
 "