calculate index of each instruction in function and calculate block preds and succs

include/gravity/core.h

@@ -27,6 +27,7 @@ GravityBuilder gravityCreateBuilder(void);
 
 GravityFunction gravityNewFunction(GravityModule module, const char* name, GravityType functionType);
 GravityBlock gravityStartBlock(const char* name, GravityFunction function);
+void gravityCompleteFunction(GravityFunction function);
 
 int gravityGetTypeSize(GravityType type);