xcscope.el does NOT search in .h files

[Rafal Kurcz <pawlaczus@yahoo.com>]

Hello
I found that sometimes the following cscope commands do not work for
*.h C++ files:

1. cscope-find-functions-calling-this-function
- when the function calling the function is inside the struct in *.h
file
the Earth::speed() from class.h below function is not taken into
account

2. cscope-find-global-definition
- (sometimes) when the function is defined in a struct that is
contained in *.h file
speed() functions from the class.h below are not taken into account

### class.h file:
struct Earth {
  void speed () {return speed(10);}
};

struct Mars {
  int speed () {return 10;}
};

struct Sun {
  int speed;
};

### class.cpp file:
#include "class.h"

class Car {
  void speed () {return;}
};

class Bike {
  int speed () {return 10;}
};

struct Plane {
  int speed;
};

char speed (char c) {return c;}

void main()
{
  Car car;
  car.speed(10);
  car.speed();
}

Thank you for help