Cleanup: put i_maxmin members and ___kmp_size_type into traits_t

Put the duplicated i_maxmin into traits_t by adding new members max_value and
min_value. Put ___kmp_size_type into traits_t by adding member type_size.

Differential Revision: https://reviews.llvm.org/D28847


git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@293316 91177308-0d34-0410-b5e6-96231b3b80d8