Add Pc annotation

I'm intending to use this in a patched version of Fernflower to track
the original index of each local variable's STORE instruction, allowing
us to retain local variable names even if the deobfuscator is run
multiple times.

deob-annotations/src/main/java/dev/openrs2/deob/annotation/Pc.java

@@ -0,0 +1,9 @@
+package dev.openrs2.deob.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+
+@Target({ ElementType.LOCAL_VARIABLE })
+public @interface Pc {
+	int value();
+}