As for now (mid 2016), there doesn't seem to be a C/C++ package manager that stands out of the crowd. To understand the reasons behind this failure, I will try to list in this README most C/C++ package managers, highlight differences between them, then list critics that are made about them.
Note: this README is merely a gathering of personnal notes, doesn't intend to be a reference in any way.
A standard proposal : http://open-std.org/JTC1/SC22/WG21/docs/papers/2016/p0235r0.pdf