Allow augmenting CPPFLAGS from the configure command line. This generally

works, but some platform templates overwrote it without asking.

src/template/hpux

-# $PostgreSQL: pgsql/src/template/hpux,v 1.15 2006/03/11 04:38:41 momjian Exp $
+# $PostgreSQL: pgsql/src/template/hpux,v 1.16 2006/12/12 19:43:19 petere Exp $
 
-CPPFLAGS="-D_XOPEN_SOURCE_EXTENDED"
+CPPFLAGS="$CPPFLAGS -D_XOPEN_SOURCE_EXTENDED"
 
 if test "$GCC" != yes ; then
   CC="$CC -Ae"

src/template/linux

-# $PostgreSQL: pgsql/src/template/linux,v 1.28 2006/03/11 04:38:41 momjian Exp $
+# $PostgreSQL: pgsql/src/template/linux,v 1.29 2006/12/12 19:43:19 petere Exp $
 
 # Force _GNU_SOURCE on; plperl is broken with Perl 5.8.0 otherwise
-CPPFLAGS="-D_GNU_SOURCE"
+CPPFLAGS="$CPPFLAGS -D_GNU_SOURCE"