Some cleanups in SUnit-Core

[astares]

Fix #10615

[Ducasse]

got a segmentation fault... strange

postload : baseline [BaselineOfPharo] >> postload:package:

• /builds/workspace/est_and_branch_Pipeline_PR-10616/64/bootstrap-cache/vmtarget/pharo --headless Pharo10.0-PR-64bit-b5070d0.image --no-default-preferences eval --save 'Smalltalk vm parameterAt: 43 put: 32'

Segmentation fault Mon Dec 6 00:02:55 2021

/builds/workspace/est_and_branch_Pipeline_PR-10616/64/bootstrap-cache/vmtarget/pharo-vm/lib/pharo
PharoVM version:5.0-Pharo 9.0.11-961e9c4 built on Dec 3 2021 12:48:50 Compiler: 5.4.0 20160609 5.4.0 20160609 [Production Spur 64-bit VM]
Built from: CoInterpreter * VMMaker-tonel.1 uuid: 646b3f33-9e8e-0d00-a512-3a76040b381d Dec 3 2021
With:StackToRegisterMappingCogit * VMMaker-tonel.1 uuid: 646b3f33-9e8e-0d00-a512-3a76040b381d Dec 3 2021
Revision: 961e9c4 - Commit: 961e9c4 - Date: 2021-12-03 11:54:30 +0100

C stack backtrace & registers:
rax 0x1bd52ce0 rbx 0x7ffd5934ac30 rcx 0x00000000 rdx 0x000000e0
rdi 0x1bd52ce0 rsi 0x1bd52ce0 rbp 0x7ffd5934ac30 rsp 0x7ffd5934ac28
r8 0x00000000 r9 0x00000000 r10 0x00000000 r11 0x7f61b535dfa0
r12 0x00000000 r13 0x7ffd5934add8 r14 0x7ffd5934ace0 r15 0x00000000
rip 0x7f61b535dfc2
*/lib/x86_64-linux-gnu/libc.so.6(+0x14dfc2)[0x7f61b535dfc2]
/builds/workspace/pharo-vm_pharo-9/build-stockReplacement/build/vm/libPharoVMCore.so(+0xc3dac)[0x7f61b569ddac]
/builds/wor

[Ducasse]

Reopened to see if we can reproduce it.