Exclude virtual nodes from the original PC counter

It's possible that future versions of ASM will introduce additional
types of virtual node. Only counting real instructions should make this
more reliable.

Signed-off-by: Graham <gpe@openrs2.dev>

deob/src/main/java/dev/openrs2/deob/transform/OriginalPcSaveTransformer.kt

@@ -9,10 +9,8 @@ import org.objectweb.asm.tree.MethodNode
 
 class OriginalPcSaveTransformer : Transformer() {
     override fun transformCode(classPath: ClassPath, library: Library, clazz: ClassNode, method: MethodNode): Boolean {
-        for ((pc, insn) in method.instructions.withIndex()) {
-            if (insn.opcode != -1) {
-                classPath.originalPcs[insn] = pc
-            }
+        for ((pc, insn) in method.instructions.filter { it.opcode != -1 }.withIndex()) {
+            classPath.originalPcs[insn] = pc
         }
 
         return false