Improve script by processing only C files.

src/tools/pginclude/pgfixinclude

 :
 # change #include's to <> or ""
-# $PostgreSQL: pgsql/src/tools/pginclude/pgfixinclude,v 1.5 2006/03/11 04:38:42 momjian Exp $
+# $PostgreSQL: pgsql/src/tools/pginclude/pgfixinclude,v 1.6 2006/07/10 16:07:24 momjian Exp $
 
 trap "rm -f /tmp/$$.c /tmp/$$.o /tmp/$$ /tmp/$$a /tmp/$$b" 0 1 2 3 15
-find . \( -name CVS -a -prune \) -o -type f -print |
+find . \( -name CVS -a -prune \) -o -type f -name '*.[chyls]' -print |
 while read FILE
 do
 	cat "$FILE" | grep "^#include" |