pgsql: Move configure --disable-float8-byval to pg_config_manual.h

Move configure --disable-float8-byval to pg_config_manual.h

This build option was once useful to maintain compatibility with
version-0 functions, but those are no longer supported, so this option
is no longer useful for end users. We keep the option available to
developers in pg_config_manual.h so that it is easy to test the
pass-by-reference code paths without having to fire up a 32-bit
machine.

Discussion: https://www.postgresql.org/message-id/flat/f3e1e576-2749-bbd7-2d57-3f9dcf75255a(at)2ndquadrant(dot)com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/4513d8b07bf342028ca95250b6e1d759858abdd3

Modified Files
--------------
configure | 76 ----------------------------------------
configure.in | 23 ------------
doc/src/sgml/installation.sgml | 16 ---------
src/include/c.h | 6 ++++
src/include/pg_config.h.in | 8 -----
src/include/pg_config_manual.h | 13 +++++++
src/tools/msvc/Solution.pm | 15 --------
src/tools/msvc/config_default.pl | 3 --
8 files changed, 19 insertions(+), 141 deletions(-)