headers: winnt.h: remove outdated SUBLANG_* constants

The following constants are missing from winnt.h in recent Windows SDKs:

1. SUBLANG_ENGLISH_IRELAND; same as SUBLANG_ENGLISH_EIRE
2. SUBLANG_HAUSA_NIGERIA; same as SUBLANG_HAUSA_NIGERIA_LATIN
3. SUBLANG_LAO_LAO_PDR; same as SUBLANG_LAO_LAO
4. SUBLANG_LITHUANIAN_LITHUANIA; same as SUBLANG_LITHUANIAN
5. SUBLANG_PORTUGUESE_PORTUGAL; same as SUBLANG_PORTUGUESE
6. SUBLANG_SWEDISH_SWEDEN; same as SUBLANG_SWEDISH
7. SUBLANG_SYRIAC; same as SUBLANG_SYRIAC_SYRIA

Each of them is an alias to another constant; for compatibility with recent
Windows SDKs, the latter constants should be used instead.

Signed-off-by: LIU Hao <lh_mouse@126.com>