Kernel: Mark read-only PT_LOAD mappings as shared regions

This makes Region::clone() do the right thing for these now that we
differentiate based on Region::is_shared().

Kernel/Process.cpp

@@ -887,8 +887,10 @@ int Process::do_exec(NonnullRefPtr<FileDescription> main_program_description, Ve
  prot |= PROT_WRITE;
  if (is_executable)
  prot |= PROT_EXEC;
- if (auto* region = allocate_region_with_vmobject(vaddr.offset(totally_random_offset), size, *vmobject, offset_in_image, String(name), prot))
+ if (auto* region = allocate_region_with_vmobject(vaddr.offset(totally_random_offset), size, *vmobject, offset_in_image, String(name), prot)) {
+ region->set_shared(true);
  return region->vaddr().as_ptr();
+ }
  return nullptr;
  };
  loader->alloc_section_hook = [&](VirtualAddress vaddr, size_t size, size_t alignment, bool is_readable, bool is_writable, const String& name) -> u8* {