Fixes valgrind failure caused by silk_find_pred_coefs_*()

The function copies NLSFs from the stack to the state which for
order 10 means we were copying uninitialized values. That in turn
breaks check-asm when comparing the state under valgrind.

Reviewed by Timothy B. Terriberry.

silk/fixed/find_pred_coefs_FIX.c

@@ -42,7 +42,8 @@ void silk_find_pred_coefs_FIX(
 {
     opus_int         i;
     opus_int32       invGains_Q16[ MAX_NB_SUBFR ], local_gains[ MAX_NB_SUBFR ];
-    opus_int16       NLSF_Q15[ MAX_LPC_ORDER ];
+    /* Set to NLSF_Q15 to zero so we don't copy junk to the state. */
+    opus_int16       NLSF_Q15[ MAX_LPC_ORDER ]={0};
     const opus_int16 *x_ptr;
     opus_int16       *x_pre_ptr;
     VARDECL( opus_int16, LPC_in_pre );

silk/float/find_pred_coefs_FLP.c

@@ -44,7 +44,8 @@ void silk_find_pred_coefs_FLP(
     silk_float       XXLTP[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ];
     silk_float       xXLTP[ MAX_NB_SUBFR * LTP_ORDER ];
     silk_float       invGains[ MAX_NB_SUBFR ];
-    opus_int16       NLSF_Q15[ MAX_LPC_ORDER ];
+    /* Set to NLSF_Q15 to zero so we don't copy junk to the state. */
+    opus_int16       NLSF_Q15[ MAX_LPC_ORDER ]={0};
     const silk_float *x_ptr;
     silk_float       *x_pre_ptr, LPC_in_pre[ MAX_NB_SUBFR * MAX_LPC_ORDER + MAX_FRAME_LENGTH ];
     silk_float       minInvGain;