pcre2: Disable JIT SEAlloc on ELFv1 ppc64

It causes consistent segfaults when trying to use Perl regex in gnugrep.

pkgs/development/libraries/pcre2/default.nix

···
   stdenv,
   fetchurl,
   updateAutotoolsGnuConfigScriptsHook,
-  withJitSealloc ? true,
+  # Causes consistent segfaults on ELFv1 PPC64 when trying to use Perl regex in gnugrep
+  # https://github.com/PCRE2Project/pcre2/issues/762
+  withJitSealloc ? !(stdenv.hostPlatform.isPower64 && stdenv.hostPlatform.isAbiElfv1),
 }:
 
 stdenv.mkDerivation rec {