[libcxx] Add missing includes in tests
A bunch of unordered containers tests call library functions but don't directly
include the corresponding header files:
- fabs() (defined in <cmath> which is not included);
- is_permutation() (defined in <algorithm> which is not included);
- next() (defined in <iterator> which is not included).
- As a result, these tests won't compile against some conformant libraries.
Reviewed as https://reviews.llvm.org/D54643.
Thanks to Andrey Maksimov for the patch.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@347085 91177308-0d34-0410-b5e6-96231b3b80d8
21 files changed