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

Calculating dependencies ... done!
Dependency resolution took 1.02 s (backtrack: 0/20).

[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     ] dev-libs/libusb-compat-0.1.9::gentoo  USE="(split-usr) -debug -examples" 322 KiB
[ebuild  N     ] virtual/libusb-0-r2::gentoo  0 KiB
[ebuild  N     ] media-libs/libnjb-2.2.7-r2::gentoo  USE="-doc -static-libs" 487 KiB

Total: 5 packages (5 new), Size of downloads: 1449 KiB