check-static-inits: Filter out zero-length sections

When compiling with -O0, zero-sized constructors were showing up
and confusing the test.

src/check-static-inits.sh

@@ -22,7 +22,7 @@ fi
 
 echo "Checking that no object file has static initializers"
 for obj in $OBJS; do
-	if objdump -t "$obj" | grep '[.][cd]tors'; then
+	if objdump -t "$obj" | grep '[.][cd]tors' | grep -v '\<00*\>'; then
 		echo "Ouch, $obj has static initializers/finalizers"
 		stat=1
 	fi