pgsql: Add missing string terminator

Add missing string terminator

When copying the string strncpy won't add nul termination since
the string length is equal to the length specified.  Explicitly
set a nul terminator after copying to properly terminate. Found
via post-commit review.

Author: Rahila Syed <rahilasyed90@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CAH2L28vt16C9xTuK+K7QZvtA3kCNWXOEiT=gEekUw3Xxp9LVQw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d2a1ed1727a8ef45eab1a8ddb3d375c1ce839aac

Modified Files
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src/backend/utils/mmgr/mcxt.c | 1 +
1 file changed, 1 insertion(+)