drmemory causes HeapValidate to fail with FALSE return

I'm using drmemory on Windows 10 10.0.10240 Build 10240:
>Dr. Memory version 1.11.0 build 2

My test program is:

```c
#include
#include

int main(void) {
HANDLE heap = GetProcessHeap();
BOOL worked = HeapValidate(heap, 0, NULL);

if(!worked) {
printf("Invalid heap!\n"); // Output when executed with drmemory
return -1;
}
printf("Valid heap.\n"); // Output without drmemory
return 0;
}
```
When I execute my application without drmemory:
>\>./app.exe
>Valid heap.

and with drmemory:
>\>drmemory.exe -- ./app.exe
>Invalid heap!