Some implementation notes:

1. Some copy protections call NtSetLdtEntries(0x000f) and then with 'retf'
instruction jump to that selector expecting that it works (the tests show that
NtSetLdtEntries(0x000f,0x001f) should succeed). In order to make this work a
limitation to set only selectors > LDT_FIRST_ENTRY (512) in wine_ldt_set_entry()
was removed.

2. wine_ldt_set_entry() was made to always mark modified selector entries as
WINE_LDT_FLAGS_ALLOCATED, otherwise get_selector_entry() server call returns
entries without that flag set and NtQueryInformationThread(ThreadDescriptorTableEntry)
fails.