MFC r315518

MFC r315518
  Avoid unnecessary calls to vm_map_protect() in elf_load_section().

  Typically, when elf_load_section() unconditionally passed VM_PROT_ALL to
  elf_map_insert(), it was needlessly enabling execute access on the
  mapping, and it would later have to call vm_map_protect() to correct the
  mapping's access rights.  Now, instead, elf_load_section() always passes
  its parameter "prot" to elf_map_insert().  So, elf_load_section() must
  only call vm_map_protect() if it needs to remove the write access that
  was temporarily granted to perform a copyout().

Approved by:	re (kib)