The B-2 Stealth bomber could be the big loser in House-Senate jockeying over the 1992 defense-spending bill. House negotiators are showing willingness to split the difference with the Senate over Star Wars. The likely outcome: $4 billion in funding, up from the $3.5 billion originally approved by the House. Compromise legislation would also allow deployment of a ground-based missile defense. But the House plans to stand firm against buying any more of Northrop Corp.'s B-2s beyond the 15 already ordered. The Senate had funded four more planes at a cost of $3.2 billion.