Use debian/changelog timestamp for BUILD_DATE in scripts
https://reproducible.debian.net/rb-pkg/unstable/amd64/fence-agents.html

--- a/scripts/fenceparse
+++ b/scripts/fenceparse
@@ -32,7 +32,7 @@ esac
 
 awk "{print}(\$1 ~ /#BEGIN_VERSION_GENERATION/){exit 0}" $realinfile
 echo ${start}RELEASE_VERSION=\"${release}\"${end}
-echo ${start}BUILD_DATE=\"\(built $(date)\)\"${end}
+echo ${start}BUILD_DATE=\"\(built ${BUILD_DATE:-$(date)}\)\"${end}
 if awk -v p=0 "(\$1 ~ /#BEGIN_VERSION_GENERATION/){p = 1} (\$1 ~ /#END_VERSION_GENERATION/){p = 0} {if(p==1)print}" $realinfile | \
 		grep -q REDHAT_COPYRIGHT; then
 	echo ${start}REDHAT_COPYRIGHT=${definedata}${end}
