Remove enforced c++98 from nightly tests.
Remove enforced c++98 from nightly tests.


Former-commit-id: 011f3fbe1efaa40f2b88d3f86ee55d6b2bc509a6
darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide