pgsql: Strip file names reported in error messages in vpath builds

Strip file names reported in error messages in vpath builds

In vpath builds, the __FILE__ macro that is used in verbose error
reports contains the full absolute file name, which makes the error
messages excessively verbose.  So keep only the base name, thus
matching the behavior of non-vpath builds.

Branch
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REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/81a50686b884632d2e8b18ecb4c70ea2f39178d6

Modified Files
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src/backend/utils/error/elog.c |   18 ++++++++++++++++--
1 files changed, 16 insertions(+), 2 deletions(-)