Google double-conversion (reduced)

This corresponds to commit hash

04cae7a8d5ef3d62ceffb03cdc3d38f258457a52

from Google repository

https://code.google.com/p/double-conversion/

Change-Id: I68735b5450bd62e6a8d709475dce9934253d4536
COMP: Merge of DoubleConversion upstream changes.

The update procedure for DoubleConversion is described in
.../DoubleConversion/src/UpdateDoubleConversionFromGoogle.sh

The procedure is based on Brad Kings work, described here:
Modules/ThirdParty/VNL/src/README-ITK.txt

Change-Id: I0c8edc8501cb4a8469a26c2a41df4301457ac977
Merge topic 'DoubleConversion-update'

d466045 COMP: Merge of DoubleConversion upstream changes.
0447797 Google double-conversion (reduced)