cacert: remove broken includeEmail option

This doesn't do anything. Building with includeEmail = true produces
the same set as includeEmail = false, and the substitute rule removes
a random dictionary index operation.

pkgs/data/misc/cacert/default.nix

@@ -1,6 +1,5 @@
 { stdenv, fetchurl, nss, python3
 , blacklist ? []
-, includeEmail ? false
 
 # Used for tests only
 , runCommand
@@ -42,10 +41,6 @@ stdenv.mkDerivation {
     EOF
 
     cat ${certdata2pem} > certdata2pem.py
-    ${optionalString includeEmail ''
-      # Disable CAs used for mail signing
-      substituteInPlace certdata2pem.py --replace \[\'CKA_TRUST_EMAIL_PROTECTION\'\] '''
-    ''}
   '';
 
   buildPhase = ''