pgsql: Remove separate version numbering for ecpg preprocessor.

Remove separate version numbering for ecpg preprocessor.

Once upon a time, it made sense for the ecpg preprocessor to have its
own version number, because it used a manually-maintained grammar that
wasn't always in sync with the core grammar. But those days are
thankfully long gone, leaving only a maintenance nuisance behind.
Let's use the PG v10 version numbering changeover as an excuse to get
rid of the ecpg version number and just have ecpg identify itself by
PG_VERSION. From the user's standpoint, ecpg will go from "4.12" in
the 9.6 branch to "10" in the 10 branch, so there's no failure of
monotonicity.

Discussion: <1471332659(dot)4410(dot)67(dot)camel(at)postgresql(dot)org>

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/a7b5573d665c8a37fad9bc69f44c5b4e8760a73b

Modified Files
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src/interfaces/ecpg/preproc/Makefile | 9 ++-------
src/interfaces/ecpg/preproc/ecpg.c | 10 +++++-----
src/tools/RELEASE_CHANGES | 4 +---
src/tools/msvc/Mkvcbuild.pm | 3 ---
4 files changed, 8 insertions(+), 18 deletions(-)