limits.h currently interferes with Clang's limits.h. include_next
emits a warning because it is a GNU extension. Will re add this once
we figure out a good solution.
This reverts commits 13bbca8d694b4ef2ad03ec1805f07da8640c1a31,
002cba03298a7e8f0c1cadcb7996379e9ea5feff, and
0fb3066873fdfbe28dbb6409c58a8bff7cf208c6.