pcre2test: print max stack size in the right units

[carenas]

on a side note; do we really need to test with 64MB of stack nowadays? if I recall correctly the limit might had been increased because of some platforms that couldn't run without it (maybe Linux/m68k) but that was before 10.30 where the possibility of stack overflows was more likely.

AFAIK macOS uses 8M by default and was failing the -S call because the maximum allowed is a little less than 64M and therefore has been running fine with only that much (even before the latest improvements in 10.41)

if anything, and considering the trend to have multiple threads I would expect we should be instead looking at restricting the stack size (less than 1MB per thread stack size is IMHO common).

[carenas]

FWIW successfully tested 10.41 in a Solaris 11 system built with Developer Studio 12.6 WITHOUT setting -M 64 to pcre2test

[PhilipHazel]

This patch wasn't quite right for cases where the hard limit is not a whole number of MiB. I have done some more work so that now the value is shown in MiB if it is a whole number of MiB, else in KiB if it is a whole number of KiB - which is most likely since "ulimit -s" works in KiB - or else in bytes. I find I still need a large stack in order to run the tests when compiling with Clang's sanitize options.