test: fix busybox realpath compat

busybox realpath doesn't have the -e option. The option
didn't seem to be needed anyways so remove it. 

test/solver.sh

@@ -18,7 +18,7 @@ run_test() {
 	local test="$1"
 	local testfile testdir
 
-	testfile="$(realpath -e "$test")"
+	testfile="$(realpath "$test")"
 	testdir="$(dirname "$testfile")"
 
 	setup_apkroot