pgsql: Fix makefile logic to not break the build when xgettext is missi

Fix makefile logic to not break the build when xgettext is missing

xgettext is only required when make init-po is run manually; it is not
required for a build.  The intent to handle that was already there, but
the ifdef's were in the wrong place.

Branch
------
master

Details
-------
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=30e749dece0e6502d4dd0a3b2892eab61f8c073b

Modified Files
--------------
src/nls-global.mk |   12 ++++++++----
1 files changed, 8 insertions(+), 4 deletions(-)