[clang-tidy] Don't generate fixes for initializer_list constructor in make_unique check.

Summary:
The current fix will break the compilation -- because braced list is not
deducible in std::make_unique (with the use of forwarding) without
specifying the type explicitly.

We could support it in the future.

Reviewers: alexfh

Reviewed By: alexfh

Subscribers: JDevlieghere, xazax.hun, cfe-commits

Differential Revision: https://reviews.llvm.org/D36786

llvm-svn: 311078