Add support for frame resizing. Handle old stream frame type in encoder.

TNC/HdlcFrame.hpp

@@ -101,6 +101,7 @@ public:
     }
 
     uint16_t size() const {return data_.size();}
+    bool resize(uint16_t size) {return data_.resize(size);}
 
     uint16_t crc() const {return crc_;}
     uint16_t fcs() const {return fcs_;}

TNC/M17Encoder.cpp

@@ -225,6 +225,12 @@ void M17Encoder::process_stream(tnc::hdlc::IoFrame* frame, FrameType type)
         {
             send_stream(frame, type);   // Consumes frame.
         }
+        else if (frame->size() == 26)
+        {
+            // Old-style frame with trailing CRC.
+            frame->resize(24);
+            send_stream(frame, type);
+        }
         else
         {
             WARN("Unexpected AUDIO frame size = %u", frame->size());

TNC/SegmentedBuffer.hpp

@@ -81,6 +81,23 @@ struct SegmentedBuffer {
 
     uint16_t size() const {return size_;}
 
+    bool resize(uint16_t size)
+    {
+        if (size <= size_)
+        {
+            size_ = size;
+        }
+        else
+        {
+            for (;size_ != size;)
+            {
+                if (!push_back(value_type()))
+                    return false;
+            }
+        }
+        return true;
+    }
+
     bool push_back(value_type value) {
         uint16_t offset = size_ & 0xFF;
         if (offset == 0) { // Must allocate.