pgsql: Fix one-byte buffer overrun in contrib/test_parser.

Fix one-byte buffer overrun in contrib/test_parser.

The original coding examined the next character before verifying that
there *is* a next character.  In the worst case with the input buffer
right up against the end of memory, this would result in a segfault.

Problem spotted by Paul Guyot; this commit extends his patch to fix an
additional case.  In addition, make the code a tad more readable by not
overloading the usage of *tlen.

Branch
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REL8_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/23bd628b9fb912292496670d6dc42719a7fd1951

Modified Files
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contrib/test_parser/test_parser.c |   19 ++++++++++---------
1 files changed, 10 insertions(+), 9 deletions(-)