memset string pages to zero to avoid putting random data on the stack
 that may make some program crash at startup.
Fix unsigned long / target_ulong confusion (more to do).
Fix missing g2h macros.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3249 c046a42c-6fe2-441c-8c8c-71466251a162
