pgsql: Update src/tools/make_ctags to avoid Exuberant tags option

Update src/tools/make_ctags to avoid Exuberant tags option
that has been renamed and undocumented since 2003;  instead, use the
documented option.  Add comments.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/7c19f9d139e76529bbb94b1bde7bc4c19f1bc37a

Modified Files
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src/tools/make_ctags |   41 +++++++++++++++++++++++++++++++----------
1 files changed, 31 insertions(+), 10 deletions(-)