pgsql: Fix configure's incorrect version tests for flex and perl.

Fix configure's incorrect version tests for flex and perl.

awk's equality-comparison operator is "==" not "=". We got this right
in many places, but not in configure's checks for supported version
numbers of flex and perl. It hadn't been noticed because unsupported
versions are so old as to be basically extinct in the wild, and because
the only consequence is whether or not a WARNING flies by during
configure.

Daniel Gustafsson noted the problem with respect to the test for flex,
I found the other by reviewing other awk calls.

Branch
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REL9_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/1ba874505f903296dfc4cc156dc1601cd8f8d531

Modified Files
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config/perl.m4 | 2 +-
config/programs.m4 | 2 +-
configure | 4 ++--
3 files changed, 4 insertions(+), 4 deletions(-)