GCC 4.8 doesn't even understand --std=c++14

Bug: b/147359661
Change-Id: I5189d24638007ffe40e8903a382bccab9ef1c0fc
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/39950Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>