check library was built before comparing with symbols file

Git-Dch: Ignore

prepare-release

@@ -127,9 +127,14 @@ elif [ "$1" = 'post-build' ]; then
 
 elif [ "$1" = 'library' ]; then
 	librarysymbols() {
-		echo "Checking $1 in version $2"
+		local buildlib="build/bin/${1}.so.${2}"
+		if [ ! -r "$buildlib" ]; then
+			echo "ERROR: The library ${1} has to be built before symbols can be checked!"
+			return
+		fi
+		echo "Checking $1 in version $2 build at $(stat -L -c '%y' "$buildlib")"
 		local tmpfile=$(mktemp)
-		dpkg-gensymbols -p${1}${2} -ebuild/bin/${1}.so.${2} -Idebian/${1}${2}.symbols -O/dev/null 2> /dev/null > $tmpfile || true
+		dpkg-gensymbols -p${1}${2} -e${buildlib} -Idebian/${1}${2}.symbols -O/dev/null 2> /dev/null > $tmpfile || true
 		librarysymbolsfromfile "$tmpfile" "$(echo "${1}" | cut -c 4- | tr -d '-' | tr 'a-z' 'A-Z')_${2}"
 		rm -f $tmpfile
 	}