[teruteru128]

filters_add() currently discards the result of pcre2_jit_compile():

// attempt to JIT. ignore error
(void) pcre2_jit_compile(re,PCRE2_JIT_COMPLETE);

When that call fails, matching quietly falls back to the interpreter.
DOFILTER runs pcre2_match() once per filter for every key that is
generated, so this is the hottest path in a PCRE2 build, and nothing
tells the user that it is now running the slow way.

It fails in two situations that are easy to walk into: a PCRE2 built
without JIT support, where every pattern comes back with "bad JIT
option", and a system that refuses the executable mapping JIT needs,
such as a hardened kernel or a W^X policy. Oversized patterns are not
the concern here; the compiler's own "regular expression is too large"
limit is reached first and is already reported.

This warns once, and only when not running quietly, so a filter file
with a thousand patterns still produces a single line. JIT failure stays
non-fatal, and nothing is printed when JIT succeeds.

Tested by forcing pcre2_jit_compile() to fail with a bad option:
one warning is printed for a file with several filters, -q suppresses
it, and an unmodified build stays silent.