Fix compiler warnings

- celt/modes.c:430:14: warning: cast from 'const unsigned char *' to
  'opus_int16 *' increases required alignment from 1 to 2 [-Wcast-align]
- 'C[0][1]' may be used uninitialized [-Wmaybe-uninitialized]
- Unused variable/parameter
- Value stored is never read
- MSVC warnings about "possible loss of data" due to type conversions
- MSVC warning C4146: unary minus operator applied to unsigned type
- silk/NLSF_del_dec_quant.c:137:20: warning: array subscript is above
  array bounds [-Warray-bounds] (gcc -O3 false positive)
- src/mlp_train.h:39:20: warning: function declaration isn't a prototype
  [-Wstrict-prototypes]
- Remove SMALL_FOOTPRINT code from SSE 4.1 FIR implementation, matching
  the C implementation.

The clang -Wcast-align warnings with SSE intrinsics are a known
clang issue: https://llvm.org/bugs/show_bug.cgi?id=20670

1 files changed, 4 insertions, 3 deletions

diff --git a/silk/float/schur_FLP.c b/silk/float/schur_FLP.c
index f4b4072f..c1e0bbb5 100644
--- a/silk/float/schur_FLP.c
+++ b/silk/float/schur_FLP.c
@@ -41,12 +41,13 @@ silk_float silk_schur_FLP(                  /* O    returns residual energy
     double C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ];
     double Ctmp1, Ctmp2, rc_tmp;
 
-    silk_assert( order <= SILK_MAX_ORDER_LPC );
+    silk_assert( order >= 0 && order <= SILK_MAX_ORDER_LPC );
 
     /* Copy correlations */
-    for( k = 0; k < order+1; k++ ) {
+    k = 0;
+    do {
         C[ k ][ 0 ] = C[ k ][ 1 ] = auto_corr[ k ];
-    }
+    } while( ++k <= order );
 
     for( k = 0; k < order; k++ ) {
         /* Get reflection coefficient */