pgsql: Fix join_path_components() to not add a leading slash when joini

Fix join_path_components() to not add a leading slash when joining to an
initial null string.

Per report from Robert Haas in testing psql \ir.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/fd6dbc24ef1dc6b39a795b5e0e959cf500ad71d6

Modified Files
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src/port/path.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)