pgsql-server: Use 'override' when appending text to LDFLAGS, so the

Log Message:
-----------
Use 'override' when appending text to LDFLAGS, so the build doesn't break
if the user has defined LDFLAGS themselves.

Modified Files:
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pgsql-server/src:
Makefile.global.in (r1.195 -> r1.196)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/Makefile.global.in.diff?r1=1.195&r2=1.196)