Thread: pgsql: Add missing include guard to win32ntdll.h.

Add missing include guard to win32ntdll.h.

Oversight in commit e2f0f8ed.  Also add this file to the exclusion lists
in headerscheck and cpluscpluscheck, because Unix systems don't have a
header it includes.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/2760528.1641929756%40sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/af9e6331aeba149c93052c3549140082a85a3cf9

Modified Files
--------------
src/include/port/win32ntdll.h      | 5 +++++
src/tools/pginclude/cpluspluscheck | 1 +
src/tools/pginclude/headerscheck   | 1 +
3 files changed, 7 insertions(+)