Fix usage of nonstandard uint type

[jtanx]

This type doesn't exist on windows; e.g.

/heaptrack/src/util/pointermap.h:63:46: error: 'uint' does not nam
e a type; did you mean 'int'?
   63 |         allocationIndex->index = static_cast<uint>(set.size());
      |                                              ^~~~
      |                                              int