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

Calculating dependencies ... done!
Dependency resolution took 1.09 s (backtrack: 0/20).

[ebuild  N     ] media-libs/giflib-6.1.3:0/7::gentoo  USE="-doc -static-libs" 460 KiB
[ebuild  N     ] media-libs/glm-1.0.3::gentoo  USE="-test" CPU_FLAGS_X86="avx avx2 sse2 sse3 sse4_1 sse4_2 ssse3" 4490 KiB
[ebuild  N     ] media-libs/libwebp-1.6.0:0/7::gentoo  USE="gif jpeg opengl png tiff -static-libs -swap-16bit-csp" CPU_FLAGS_X86="avx2 sse2 sse4_1" 4196 KiB
[ebuild  N     ] x11-libs/libXcomposite-0.4.7::gentoo  USE="-doc" 267 KiB
[ebuild  N     ] media-libs/glew-2.2.0-r1:0/2.2::gentoo  USE="-doc -egl-only -static-libs" 817 KiB
[ebuild  N     ] x11-misc/slop-7.7-r1:0/7.7::gentoo  USE="opengl -icu" 194 KiB
[ebuild  N     ] media-gfx/maim-5.8.2::gentoo  USE="-icu" 41 KiB

Total: 7 packages (7 new), Size of downloads: 10462 KiB