Change ifdef to include any libc++ LLVM implementaion (#1727)
Change ifdef to include any libc++ LLVM implementaion (#1727)

Signed-off-by: Ahmed Sobhy <4e7ceaf235c69d2e5ac3ee2d5066e4acc11da4f4@blackberry.com>
eProsima/Fast-RTPS,eProsima/Fast-RTPS,eProsima/Fast-DDS,eProsima/Fast-RTPS,eProsima/Fast-RTPS,eProsima/Fast-DDS,eProsima/Fast-DDS,eProsima/Fast-DDS,eProsima/Fast-DDS,eProsima/Fast-RTPS