tests/malloccrt: one leak sometimes POSSIBLE instead of definite LEAK

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on July 28, 2011 17:06:29_

happens on win7 laptop.
nondet, only when running in parallel.
malloccrt test fails on win7 laptop:

20: CMake Error at runtest.cmake:352 (message):
20: stderr failed to match ":::Dr.Memory::: 3 unique, 3 total, 155 byte(s)
?", found ":::Dr.Memory::: 2 unique, 2 total, 96 byte(s) of
20: leak(s)" instead
20:
20:
2/2 Test `#20`: malloccrt ........................***Failed 6.40 sec

b/c this one was considered POSSIBLE instead of for sure:
Error `#8`: POSSIBLE LEAK 42 direct bytes 0x0008d350-0x0008d37a + 17 indirect bytes
0x013c152f malloccrt.exe!main
c:\src\drmemory\git\src\tests\malloc.c:219

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=522_