Allow func_curl to exit gracefully if list allocation fails during write

Allow func_curl to exit gracefully if list allocation fails during write

If the global_curl_info data structure could not be allocated, the
datastore associated with the operation would be free'd, but the function
would not return.  This would later dereference the datastore, almost
certainly causing Asterisk to crash.  With this patch, if the data
structure is not allocated the method will return an error code, and
not attempt any further operation.
........

Merged revisions 361753 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 361754 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@361755 65c4cc65-6c06-0410-ace0-fbb531ad65f3