fix: let Wine write hooks into code FEX has translated
Wine 11's wineserver writes another process's memory with process_vm_writev,
which the kernel refuses on a page that is not writable. FEX's WoW64 layer
keeps the pages it has translated read-only to catch self-modifying code and
re-protects them right after a program unprotects them, so WriteProcessMemory
and NtWriteVirtualMemory into ntdll failed with a partial copy and Ubisoft
games stopped at "Error at hooking API NtProtectVirtualMemory". Wine only
falls back to /proc/<pid>/mem on ENOSYS or EPERM.
libblsession now completes a single-buffer write that wineserver was refused
with EFAULT through /proc/<pid>/mem, the way Wine wrote before Wine 11. Other
programs and every other error keep the kernel's answer. The iovecs are read
with process_vm_readv, so a bad pointer still returns EFAULT, and offsets are
64-bit in the i386 build.
