depcheck: ensure that missing RDEPEND is also reported during a virtual check

It was failing due to a difference in return code handling:
	a() {
        	local x=$(false)
	        echo $?
	}

	b() {
        	local x
	        x=$(false)
        	echo $?
	}
	a
	b

returning:
	0
	1

1 files changed, 2 insertions, 1 deletions

diff --git a/depcheck b/depcheck
index dae0cd9..93abeb1 100755
--- a/depcheck
+++ b/depcheck
@@ -58,7 +58,8 @@ virtualcheck() {
 	for virtual in $(qdepends --nocolor --name-only --${1} --query ${libowner_pn} | grep ^virtual/)
 	do
 		debug Checking if ${virtual} is in dependencies
-		local isvirtualdep=$(qdepends --${1} ${atom} | grep ${virtual})
+		local isvirtualdep
+		isvirtualdep=$(qdepends --${1} ${atom} | grep ${virtual})
 
 		if [ $? -eq 0 ]; then
 			used_virtuals+=( ${virtual} )