Try to allocate larger buffer size instead of immediately returning error when converting pjsip_hdr to SipHeader

[riza]

Method SipHeader::fromPj() which converts pjsip_hdr to SipHeader, uses a local char array with a fixed size of 256 to buffer information from the pjsip_hdr.

This buffer is quite small, which leads to an unnecessary exception when large headers are exchanged. In one instance we encountered such an exception while receiving a large “Authorization”-Header.

This patch will try to allocate larger buffer space, instead of returning error on the first try.

Thanks to David Wichter for the report.

[riza]

In 5669:

Close #2049: Try to allocate larger buffer size when converting pjsip_hdr to
SipHeader?.