pgsql: Remove restriction on SQL block length in isolationtester scanne

Remove restriction on SQL block length in isolationtester scanner.

specscanner.l had a fixed limit of 1024 bytes on the length of
individual SQL stanzas in an isolation test script. People are
starting to run into that, so fix it by making the buffer resizable.

Once we allow this in HEAD, it seems inevitable that somebody will
try to back-patch a test that exceeds the old limit, so back-patch
this change as a preventive measure.

Daniel Gustafsson

Discussion: https://postgr.es/m/8D628BE4-6606-4FF6-A3FF-8B2B0E9B43D0@yesql.se

Branch
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REL9_3_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/824cceded4095eb3b26d19b1a91d01eaf37c0baf

Modified Files
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src/test/isolation/specscanner.l | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)