allow Silence Insertion Descriptor (SID) frames in AMR-WB

for Asterisk as receiver
For this, the library OpenCORE-AMR must be patched. If you cannot patch your library, please, instruct your AMR-WB senders to disable their Voice Activation Detection (VAD).
issue found via report #8

opencore-amr.patch

@@ -0,0 +1,29 @@
+https://android-review.googlesource.com/298277
+https://android.googlesource.com/platform/frameworks/av/+log/master/media/libstagefright/codecs/amrwb
+https://github.com/mstorsjo/platform_external_opencore
+https://sourceforge.net/p/opencore-amr/code/
+--- opencore/codecs_v2/audio/gsm_amr/amr_wb/dec/src/mime_io.cpp	(OpenCORE-AMR 0.1.3)
++++ opencore/codecs_v2/audio/gsm_amr/amr_wb/dec/src/mime_io.cpp	(working copy)
+@@ -655,14 +647,19 @@ void mime_unsorting(uint8 unsorted_bits[
+         }
+     }
+
+-    if (unpacked_size[*mode] % 4)
++    temp = *unsorted_bits_ptr; /* convert the remaining 0 to 7 bits */
++    for (i = unpacked_size[*mode] % 8; i != 0; i--)
+     {
+-        temp <<= 1;
+-
+         if (temp & 0x80)
+         {
+             sorted_bits_into_int16[*(pt_AmrWbSortingTables++)] = BIT_1;
+         }
++        else
++        {
++            pt_AmrWbSortingTables++;
++        }
++
++        temp <<= 1;
+     }
+
+     /* set frame type */