Fix unlikely but possible race in `WeakValueDictionary`
It may happen that value in `valueArray` could have been already
collected by the GC but #clearDeadSlots have not yet been called.
When this happened, `#at:ifAbsentPut:` returned tombstone rather
than updating the dictionary with value from block.
This commit fixes this by checking whether `valueArray` contain
the tombstone and if so, clearing up the dead slots and restarting
the operation. HTH.
@REM -------
@REM make using Borland bcc32
@REM type bmake, and wait...
@REM do not edit - automatically generated from ProjectDefinition
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@SET DEFINES=
@REM Kludge got Mercurial, cannot be implemented in Borland make
@FOR /F "tokens=*" %%i in ('hg root') do SET HGROOT=%%i
@IF "%HGROOT%" NEQ "" SET DEFINES=%DEFINES% "-DHGROOT=%HGROOT%"
make.exe -N -f bc.mak %DEFINES% %*