Guard against num_components being a ridiculous value due to a corrupt header

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@830 632fc199-4ca6-4c93-a231-07263d6284db

diff --cc ChangeLog.txt
index 98481ec2f036160c97eb1f1aa961d0bf46d0f6f7,3775d5439b4eda4678513a3493384ad96299cf97..475d830958cca47fb9171678f7a2bc82ada26697
--- 1/ChangeLog.txt
--- 2/ChangeLog.txt
+++ b/ChangeLog.txt
@@@ -30,6 -15,10 +30,10 @@@ so this was an attempt to make them hap
  upper 64 bits of xmm6 and xmm7 on Win64 platforms, which violated the Win64
  calling conventions.
  
 -[4] Fixed a regression caused by 1.2.0[6] whereby decompressing corrupt JPEG
++[7] Fixed a regression caused by 1.2.0[6] in which decompressing corrupt JPEG
+ images (specifically, images in which the component count was erroneously set
+ to a large value) would cause libjpeg-turbo to segfault.
+ 
  
  1.2.0
  =====