fix configure message for multi-thread

it's not just decoding, but general multi-threading

Change-Id: I9d1b7e14f05b93a0eb92955526b7019c2b0df20c
move WebPPictureInit to picture.c

Change-Id: I4b8c352cfd47256d0c3827334a6942c1caf742f6
Merge "move WebPPictureInit to picture.c"
Actuate memory stats for PRINT_MEMORY_INFO

Change-Id: If7eac591b5205990ca452ca02b084a908482850a
use explicit size of kErrorMessages[] arrays

Change-Id: If02864e3a07ae37814bf379bf347862cd2871bf4
JPEG decoder: delay conversion to YUV to WebPEncode() call

We store the raw RGB samples decoded from JPEG, and avoid precision loss.

Note that this may increase the encoding time reported by
cwebp -v, since RGB->YUV now occur during WebPEncode call
(in case of lossy), instead of ReadJPEG().
This also increases the memory use, since we're carying the
source ARGB samples around.

Change-Id: Ic2180206cfc9f5574f391e91c3b89b9d81695d01
Merge "Actuate memory stats for PRINT_MEMORY_INFO"
Merge "use explicit size of kErrorMessages[] arrays"
Extend MakeARGB32() to accept Alpha channel.

Change-Id: I31b8e2d085000e2e3687a373401e4f655f11fc42