nss: fix error messages for CURLE_SSL_{CACERT,CRL}_BADFILE

Do not use the error messages from NSS for errors not occurring in NSS.

RELEASE-NOTES

@@ -28,6 +28,7 @@ This release includes the following bugfixes:
  o build: fix AIX compilation and usage of events/revents
  o VC Makefiles: add missing hostcheck
  o nss: clear session cache if a client certificate from file is used
+ o nss: fix error messages for CURLE_SSL_{CACERT,CRL}_BADFILE
 
 This release includes the following known bugs:
 

lib/nss.c

@@ -1093,10 +1093,8 @@ static bool is_nss_error(CURLcode err)
   switch(err) {
   case CURLE_PEER_FAILED_VERIFICATION:
   case CURLE_SSL_CACERT:
-  case CURLE_SSL_CACERT_BADFILE:
   case CURLE_SSL_CERTPROBLEM:
   case CURLE_SSL_CONNECT_ERROR:
-  case CURLE_SSL_CRL_BADFILE:
   case CURLE_SSL_ISSUER_ERROR:
     return true;