Caused by 2fcd8c12. It used the documented pcre API

 -pcre_exec(NULL, NULL, NULL, -999, -999, 0, NULL, 0)

to calculate the pcre stack frame size. Unfortunately, modern compilers
broke it by cloning and inlining pcre match() function. 2fcd8c12
tried to workaround it by setting the stack frame size to at least 500.
It didn't work, 500 is not a universal constant.

Now we fix our copy of pcre to not inline or clone match() - so that
stack frame detection would work again - and detect at cmake time
whether system pcre is broken or usable.

Also use stack, not (much slower) malloc in bundled pcre, unless on Windows