Add the C++11 feature macros for ICC 15 and complete for 14

ICC 14 (Intel Composer XE 2013) already supported range for and explicit
conversions, but looks like we missed adding them.

ICC 15 (Intel Composer XE 2015) is C++11 language feature complete.

Change-Id: I6eb8a3059f5df3604716666311aa01a6cf01918d
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>