pgsql: pg_waldump: Remove file-level global WalSegSz.

pg_waldump: Remove file-level global WalSegSz.

It's better style to pass the value around to just the places that
need it. This makes it easier to determine whether the value is
always properly initialized before use.

Reviewed-by: Amul Sul <sulamul@gmail.com>
Discussion: http://postgr.es/m/CAAJ_b94+wObPn-z1VECipnSFhjMJ+R2cpTmKVYLjyQuVn+B5QA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/9a446d0256dc8f4afb4dba97734b46447c08d918

Modified Files
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src/bin/pg_waldump/pg_waldump.c | 37 +++++++++++++++++++------------------
1 file changed, 19 insertions(+), 18 deletions(-)