Don't try to shift more bits than the variable length

Shifting by more than (or equal to) the variable length is
undefined in C.

This caused the quantized spectrum values to go out of range,
triggering asserts later.

Change-Id: If81b6c8caa7b9c75941ad9d280b686d2069c968c

libAACenc/src/quantize.cpp

@@ -127,7 +127,10 @@ static void FDKaacEnc_quantizeLines(INT      gain,
       accu = fMultDiv2(FDKaacEnc_mTab_3_4[tabIndex],FDKaacEnc_quantTableE[totalShift&3]);
       totalShift = (16-4)-(3*(totalShift>>2));
       FDK_ASSERT(totalShift >=0); /* MAX_QUANT_VIOLATION */
-      accu>>=totalShift;
+      if (totalShift < 32)
+          accu>>=totalShift;
+      else
+          accu = 0;
       quaSpectrum[line] = (SHORT)(-((LONG)(k + accu) >> (DFRACT_BITS-1-16)));
     }
     else if(accu > FL2FXCONST_DBL(0.0f))
@@ -140,7 +143,10 @@ static void FDKaacEnc_quantizeLines(INT      gain,
       accu = fMultDiv2(FDKaacEnc_mTab_3_4[tabIndex],FDKaacEnc_quantTableE[totalShift&3]);
       totalShift = (16-4)-(3*(totalShift>>2));
       FDK_ASSERT(totalShift >=0); /* MAX_QUANT_VIOLATION */
-      accu>>=totalShift;
+      if (totalShift < 32)
+          accu>>=totalShift;
+      else
+          accu = 0;
       quaSpectrum[line] = (SHORT)((LONG)(k + accu) >> (DFRACT_BITS-1-16));
     }
     else