arcanist: Update certs to fix letsencrypt

Due to the old root certificate used by letsencrypt expiring, arcanist
could not connect anymore to servers using letsencrypt (like
reviews.llvm.org).

Fix it by using the default nix certificates.

pkgs/development/tools/misc/arcanist/default.nix

@@ -1,4 +1,5 @@
 { bison
+, cacert
 , fetchFromGitHub
 , flex
 , php
@@ -53,6 +54,7 @@ stdenv.mkDerivation {
     make install  -C support/xhpast $makeFlags "''${makeFlagsArray[@]}" -j $NIX_BUILD_CORES
     make cleanall -C support/xhpast $makeFlags "''${makeFlagsArray[@]}" -j $NIX_BUILD_CORES
     cp -R . $out/libexec/arcanist
+    ln -sf ${cacert}/etc/ssl/certs/ca-bundle.crt $out/libexec/arcanist/resources/ssl/default.pem
 
     ${makeArcWrapper "arc"}
     ${makeArcWrapper "phage"}