Add JPEG image support

Packages describing “jpeg” as local USE flag

Package “jpeg” Flag Description
media-video/mpv Enable support for saving screenshots in JPEG format
media-libs/imlib2 Jpeg image loader support
sci-electronics/pcb JPEG graphics export
app-emulation/qemu Enable jpeg image support for the VNC console server
gui-apps/grim Enable JPEG support.
gui-libs/neatvnc Enable fast encodings
x11-wm/ctwm Enable jpeg image support with virtual/jpeg

All packages providing a “jpeg” USE flag (102)