pgsql: Code coverage testing with gcov.

Log Message:
-----------
Code coverage testing with gcov. Documentation is in the regression test
chapter.

Author: Michelle Caisse <Michelle.Caisse@Sun.COM>

Modified Files:
--------------
pgsql:
GNUmakefile.in (r1.47 -> r1.48)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/GNUmakefile.in?r1=1.47&amp;r2=1.48)
configure (r1.604 -> r1.605)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure?r1=1.604&amp;r2=1.605)
configure.in (r1.565 -> r1.566)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure.in?r1=1.565&amp;r2=1.566)
pgsql/doc/src/sgml:
installation.sgml (r1.312 -> r1.313)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/installation.sgml?r1=1.312&amp;r2=1.313)
regress.sgml (r1.59 -> r1.60)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/regress.sgml?r1=1.59&amp;r2=1.60)
pgsql/src:
Makefile.global.in (r1.242 -> r1.243)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/Makefile.global.in?r1=1.242&amp;r2=1.243)
pgsql/src/backend:
common.mk (r1.7 -> r1.8)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/common.mk?r1=1.7&amp;r2=1.8)