Refactor sym_upload in tools to extract code into common/linux, and minor fixes

src/common/linux/http_upload.h

 // Copyright (c) 2006, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 56 matching lines @@
                           string *response_body,
                           long *response_code,
                           string *error_description);
 
  private:
   // Checks that the given list of parameters has only printable
   // ASCII characters in the parameter name, and does not contain
   // any quote (") characters.  Returns true if so.
   static bool CheckParameters(const map<string, string> &parameters);
 
+  // Checks the curl_lib parameter points to a valid curl lib.
+  static bool CheckCurlLib(void* curl_lib);
+
   // No instances of this class should be created.
   // Disallow all constructors, destructors, and operator=.
   HTTPUpload();
   explicit HTTPUpload(const HTTPUpload &);
   void operator=(const HTTPUpload &);
   ~HTTPUpload();
 };
 
 }  // namespace google_breakpad
 
 #endif  // COMMON_LINUX_HTTP_UPLOAD_H__