Workaround apps that make assumptions about pointer ids.

Modified the touch input mapper to assign pointer ids sequentially
starting from 0 instead of using the tracking id or slot index
supplied by the driver.  Applications should not depend on this
ordering but some do.  (sigh)

Bug: 4980884
Change-Id: I0dfeb3ac27c57a7102a13c960c760e2a02eb7669

include/utils/BitSet.h

@@ -44,6 +44,9 @@ struct BitSet32 {
     // Returns true if the bit set does not contain any marked bits.
     inline bool isEmpty() const { return ! value; }
 
+    // Returns true if the bit set does not contain any unmarked bits.
+    inline bool isFull() const { return value == 0xffffffff; }
+
     // Returns true if the specified bit is marked.
     inline bool hasBit(uint32_t n) const { return value & valueForBit(n); }