Fix ECPG compiler warning.

Commit 9b4d52f2095be96ca238ce41f6963ec56376491f failed to notice
that pg_regress_ecpg needed updating.

This patch was independently submitted by both David Rowley
and Andres Freund.
Fix whitespace issues found by git diff --check, add gitattributes

Set per file type attributes in .gitattributes to fine-tune whitespace
checks.  With the associated cleanups, the tree is now clean for git