tweak rejection of common 3 byte sequences

src/similarity.c

@@ -109,18 +109,16 @@ int main(int argc,char **argv)
 	  if (f1[i]==0xb0) break;
 	  if (f1[i]==0x10) break;
 
-	  if (f1[i+1]==0x85) {
-	    // Single byte followed by STA $xx
-	    // Super common, so can be ignored.
-	    break;
-	  }
-
 	  // Common 2-byte instructions followed by
 	  // any single byte are very common and not
 	  // copyrightable.
 	  if (f1[i]==0x85) break;
 	  if (f1[i]==0xa9) break;
 	  if (f1[i]==0xc9) break;
+	  // Similarly for random byte before such instructions
+	  if (f1[i+1]==0x85) break;
+	  if (f1[i+1]==0xa9) break;
+	  if (f1[i+1]==0xc9) break;
 	  
 	  // Filter out all 3 byte instructions
 	  switch(f1[i]) {