The Android project has extend the libjpeg library. These extensions have been
ported into libjpeg-turbo. 

By default none of these extentions are included. In order to enable the
Android extentions the following defines must be included with CFLAGS.

-DANDROID -DANDROID_TILE_BASED_DECODE -DANDROID_RGB -DENABLE_ANDROID_NULL_CONVERT

Android does not utilize the autotools as a mechanism for configuration, 
creation of Makefiles and such. Instead Android.mk has been included.
However two generated files are expected, config.h and jconfig.h. Both of these
files are included in the android directory. 

To build on android. Place the libjpeg-turbo directory into system/external. Remove the
old jpeg directory. Rename libjpeg-turbo to jpeg. Copy the contents of the android
directory into the main libjpeg-turbo directory. 

Build your android as your normally would.

This code (until accepted upstream) is being kept in the 1.2-beta-linaro-andoid branch
in git at:

http://git.linaro.org/gitweb?p=people/tomgall/libjpeg-turbo/libjpeg-turbo.git;a=summary

If you have questions feel free to email tom.gall@linaro.org or join #linaro
on irc.freenode.net and ping tgall_foo/Dr_Who.

Enjoy!