fix makefile pkg-config sdl2 detection
Merge pull request #129 from jdeseno/master

fix makefile pkg-config sdl2 detection
complete cpu api
Merge pull request #132 from jdeseno/cpuinfo

complete cpu api
Merge pull request #131 from bvssvni/master

Added rust-empty.mk
complete clipboard api
Merge pull request #133 from jdeseno/clipboard

complete clipboard api
complete filesystem api
Merge pull request #134 from jdeseno/filesystem

complete filesystem api
Upgrade to latest Rust