Add X509 certificate and CRL MIME-types

Add the following MIME types:
- application/pkix-cert
- application/pkix-crl
- application/x-pem-file

src/civetweb.c

@@ -8511,6 +8511,9 @@ static const struct {
      * (http://www.iana.org/assignments/media-types)
      * application types */
     {".bin", 4, "application/octet-stream"},
+    {".cer", 4, "application/pkix-cert"},
+    {".crl", 4, "application/pkix-crl"},
+    {".crt", 4, "application/pkix-cert"},
     {".deb", 4, "application/octet-stream"},
     {".dmg", 4, "application/octet-stream"},
     {".dll", 4, "application/octet-stream"},
@@ -8522,6 +8525,7 @@ static const struct {
     {".json", 5, "application/json"},
     {".mjs", 4, "application/javascript"},
     {".msi", 4, "application/octet-stream"},
+    {".pem", 4, "application/x-pem-file"},
     {".pdf", 4, "application/pdf"},
     {".ps", 3, "application/postscript"},
     {".rtf", 4, "application/rtf"},