pgsql: Fix missing dependencies in ecpg's test Makefiles.

Fix missing dependencies in ecpg's test Makefiles.

Ensure that ecpg preprocessor output files are rebuilt when re-testing
after a change in the ecpg preprocessor itself, or a change in any of
several include files that get copied verbatim into the output files.
The lack of these dependencies was what created problems for Kevin Grittner
after the recent pgindent run. There's no way for --enable-depend to
discover these dependencies automatically, so we've gotta put them into
the Makefiles by hand.

While at it, reduce the amount of duplication in the ecpg invocations.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/14d309cc55d88b73d4c9d1fa51b535ae491405fd

Modified Files
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src/interfaces/ecpg/test/Makefile.regress | 21 +++++++++++++---
src/interfaces/ecpg/test/compat_informix/Makefile | 28 +++------------------
src/interfaces/ecpg/test/preproc/Makefile | 16 ++++++------
src/interfaces/ecpg/test/sql/Makefile | 4 +--
4 files changed, 31 insertions(+), 38 deletions(-)