MT#57415 ilbc: accessing 428 bytes at offsets 0 and 160 overlaps

It's been noticed that we are using `memcpy` for copying of the data,
where the source and destination overlaps.
This begets the following warning:

     In function 'memcpy',
         inlined from 'Decode' at iLBC_decode.c:254:16:
     /usr/include/x86_64-linux-gnu/bits/string_fortified.h:34:10: warning: '__builtin_memcpy' accessing 428 bytes at offsets 0 and 160 overlaps 268 bytes at offset 160 [-Wrestrict]
        34 |   return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest));
           |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     In function 'memcpy',
         inlined from 'Decode' at iLBC_decode.c:302:16:
     /usr/include/x86_64-linux-gnu/bits/string_fortified.h:34:10: warning: '__builtin_memcpy' accessing 428 bytes at offsets 0 and 160 overlaps 268 bytes at offset 160 [-Wrestrict]
        34 |   return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest));
           |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     In file included from /usr/include/string.h:495,
                      from iLBC_encode.c:15:
     In function 'memcpy',
         inlined from 'iLBC_encode' at iLBC_encode.c:311:16:
     /usr/include/x86_64-linux-gnu/bits/string_fortified.h:34:10: warning: '__builtin_memcpy' accessing 428 bytes at offsets 0 and 160 overlaps 268 bytes at offset 160 [-Wrestrict]
        34 |   return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest));
           |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     In function 'memcpy',
         inlined from 'iLBC_encode' at iLBC_encode.c:389:16:
     /usr/include/x86_64-linux-gnu/bits/string_fortified.h:34:10: warning: '__builtin_memcpy' accessing 428 bytes at offsets 0 and 160 overlaps 268 bytes at offset 160 [-Wrestrict]
        34 |   return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest));
           |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The problem is that `memcpy` should not be used, when dst memory overlaps with src memory.
We should update such usage of `memcpy` and swap it with `memmove`

From the manpage of the `memcpy`:
>> The memory areas should not overlap. Use memmove(3) if the memory areas do overlap.

Change-Id: I5e3e65587fad92c91bb298e4e5415db1fd0c0371

core/plug-in/ilbc/iLBC_rfc3951/iLBC_decode.c

@@ -250,16 +250,8 @@
                    memLfTbl[subcount], SUBL, CB_NSTAGES);
 
                /* update memory */
-
-               memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
-               memcpy(mem+CB_MEML-SUBL,
-
-
-
-
-
-                   &decresidual[(start+1+subframe)*SUBL],
-                   SUBL*sizeof(float));
+               memmove(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
+               memcpy(mem+CB_MEML-SUBL, &decresidual[(start+1+subframe)*SUBL], SUBL*sizeof(float));
 
                subcount++;
 
@@ -298,11 +290,8 @@
                    SUBL, CB_NSTAGES);
 
                /* update memory */
-
-               memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
-               memcpy(mem+CB_MEML-SUBL,
-                   &reverseDecresidual[subframe*SUBL],
-                   SUBL*sizeof(float));
+               memmove(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
+               memcpy(mem+CB_MEML-SUBL, &reverseDecresidual[subframe*SUBL], SUBL*sizeof(float));
 
                subcount++;
            }

core/plug-in/ilbc/iLBC_rfc3951/iLBC_encode.c

@@ -307,16 +307,8 @@
                    memLfTbl[subcount], SUBL, CB_NSTAGES);
 
                /* update memory */
-
-               memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
-               memcpy(mem+CB_MEML-SUBL,
-
-
-
-
-
-                   &decresidual[(start+1+subframe)*SUBL],
-                   SUBL*sizeof(float));
+               memmove(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
+               memcpy(mem+CB_MEML-SUBL, &decresidual[(start+1+subframe)*SUBL], SUBL*sizeof(float));
                memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
 
                subcount++;
@@ -386,10 +378,8 @@
 
                /* update memory */
 
-               memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
-               memcpy(mem+CB_MEML-SUBL,
-                   &reverseDecresidual[subframe*SUBL],
-                   SUBL*sizeof(float));
+               memmove(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
+               memcpy(mem+CB_MEML-SUBL, &reverseDecresidual[subframe*SUBL], SUBL*sizeof(float));
                memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
 
                subcount++;