Fix for segmentation fault in hf generator

Number of envelopes is becoming zero because of erroneous input
stream.Inside SBR start band and stop band are calculated based
on number of envelope's.

In this case start bands is becoming negative. In sbr processing
buffer is accessed from start to stop band. This is causing OOB
read access

Bug:113037143
Test: poc
Change-Id: Iade10e8cb86676784703e7226b7e132761eb12b1
(cherry picked from commit 4e5b9cb8f61ea4c14f964fd570e6f3b7934e5255)
3 files changed