pgsql: Disable excessive FP optimization by recent versions of gcc.

Disable excessive FP optimization by recent versions of gcc.

Suggested solution from Tom Lane. Problem discovered, probably not
for the first time, while testing the mingw-w64 32 bit compiler.

Backpatched to all live branches.

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/517462faf0af96fccc3acfc30ca8242a13859ca5

Modified Files
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configure | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
configure.in | 2 ++
2 files changed, 53 insertions(+), 0 deletions(-)