vma_intersect() was erroneous, replaced by a nice and simple set_intersection() routine.

Still testing sys_munmap(). It now correctly spots and unmaps the overlapping vma.
The issue now is that if a split occurs, we forgot to add same objects to new vma.

include/l4/lib/math.h

@@ -4,4 +4,19 @@
 #define min(x, y)		(((x) < (y)) ? x : y)
 #define max(x, y)		(((x) > (y)) ? x : y)
 
+/* Tests if ranges a-b intersect with range c-d */
+static inline int set_intersection(unsigned long a, unsigned long b,
+				   unsigned long c, unsigned long d)
+{
+	/*
+	 * Below is the complement (') of the intersection
+	 * of 2 ranges, much simpler ;-)
+	 */
+	if (b <= c || a >= d)
+		return 0;
+
+	/* The rest is always intersecting */
+	return 1;
+}
+
 #endif /* __LIB_MATH_H__ */