[PATCH][meta-networking] postfix: Add explict getVar expansion parameter

[Richard Purdie <richard.purdie@linuxfoundation.org>]

Bitbake is likely to require this parameter in future, add
the default value.

Patch generated with the command: 

sed -e 's:\(getVar([^,()]*\)\s*):\1, False):g' -i `grep -ril getVar *`

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta-networking/recipes-daemons/postfix/postfix.inc b/meta-networking/recipes-daemons/postfix/postfix.inc
index fa75a78..cd768cc 100644
--- a/meta-networking/recipes-daemons/postfix/postfix.inc
+++ b/meta-networking/recipes-daemons/postfix/postfix.inc
@@ -232,7 +232,7 @@ pkg_postinst_${PN} () {
         touch $D/etc/postfix/virtual_alias
         postmap -c $D/etc/postfix $D/etc/postfix/virtual_alias
 
-        if ${@'true' if 'linuxstdbase' in d.getVar('DISTROOVERRIDES') else 'false'}; then
+        if ${@'true' if 'linuxstdbase' in d.getVar('DISTROOVERRIDES', False) else 'false'}; then
             # /usr/lib/sendmial is required by LSB core test
             [ ! -L $D/usr/lib/sendmail ] && ln -sf ${sbindir}/sendmail $D/usr/lib/
         fi