graphics/libprojectm: fix build with GCC-based architectures

There are two issues here:

1. GLM requires at least GCC 4.7, base has 4.2. Add USES=compiler:c++11-lang to solve it.
2. the port uses typedefs from sys/types.h, but those are not included by default by GCC.

PR: 233748
Submitted by: Piotr Kubaj <pkubaj@anongoth.pl>