leak from VS2017 CRT _register_onexit_function

In the operators test. Also see in procterm, state, and infloop tests.
```
2020-12-11T16:35:27.2039824Z 14: Error #2: LEAK 256 direct bytes 0x0000025ceb632670-0x0000025ceb632770 + 0 indirect bytes
2020-12-11T16:35:27.2040639Z 14: # 0 replace_RtlAllocateHeap (0x00007ff64ce92c40 )
2020-12-11T16:35:27.2041346Z 14: d:\a\drmemory\drmemory\common\alloc_replace.c:3771
2020-12-11T16:35:27.2041987Z 14: # 1 _malloc_base (0x00007ff6bccab0dc )
2020-12-11T16:35:27.2042617Z 14: minkernel\crts\ucrt\src\appcrt\heap\malloc_base.cpp:34
2020-12-11T16:35:27.2043265Z 14: # 2 _realloc_base (0x00007ff6bccb11e5 )
2020-12-11T16:35:27.2043907Z 14: minkernel\crts\ucrt\src\appcrt\heap\realloc_base.cpp:31
2020-12-11T16:35:27.2044550Z 14: # 3 _recalloc_base (0x00007ff6bccb624b )
2020-12-11T16:35:27.2045195Z 14: minkernel\crts\ucrt\src\appcrt\heap\recalloc.cpp:34
2020-12-11T16:35:27.2046062Z 14: # 4 ::operator() (0x00007ff6bcca9a17 )
2020-12-11T16:35:27.2046916Z 14: minkernel\crts\ucrt\src\appcrt\startup\onexit.cpp:112
2020-12-11T16:35:27.2047605Z 14: # 5 __crt_seh_guarded_call<>::operator()<> (0x00007ff6bcca9931 )
2020-12-11T16:35:27.2048334Z 14: minkernel\crts\ucrt\devdiv\vcruntime\inc\internal_shared.h:204
2020-12-11T16:35:27.2049078Z 14: # 6 _register_onexit_function (0x00007ff6bcca9d02 )
2020-12-11T16:35:27.2049771Z 14: minkernel\crts\ucrt\src\appcrt\startup\onexit.cpp:84
2020-12-11T16:35:27.2050389Z 14: # 7 _onexit (0x00007ff6bcc9cb4d )
2020-12-11T16:35:27.2051061Z 14: d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\utility\utility.cpp:261
2020-12-11T16:35:27.2051725Z 14: # 8 atexit (0x00007ff6bcc9cb79 )
2020-12-11T16:35:27.2052394Z 14: d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\utility\utility.cpp:275
2020-12-11T16:35:27.2053105Z 14: # 9 pre_c_initialization (0x00007ff6bcc9c6aa )
2020-12-11T16:35:27.2053835Z 14: d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:164
2020-12-11T16:35:27.2054525Z 14: #10 _initterm_e (0x00007ff6bcca821b )
2020-12-11T16:35:27.2055168Z 14: minkernel\crts\ucrt\src\appcrt\startup\initterm.cpp:40
2020-12-11T16:35:27.2055840Z 14: #11 __scrt_common_main_seh (0x00007ff6bcc9c7a4 )
2020-12-11T16:35:27.2056527Z 14: d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:253
```