These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.01 s (backtrack: 0/20).

[ebuild  N     ] acct-group/plugdev-0-r3::gentoo  0 KiB
[ebuild  N     ] dev-libs/libusb-1.0.30:1::gentoo  USE="-debug -doc -examples -static-libs -test -udev -verify-sig" 641 KiB
[ebuild  N     ] virtual/libusb-1-r2:1::gentoo  USE="-udev" 0 KiB
[ebuild  N     ] media-libs/libmtp-1.1.22:0/9::gentoo  USE="crypt -doc -examples (-selinux) -static-libs" 880 KiB

Total: 4 packages (4 new), Size of downloads: 1521 KiB