scripts: frag2inc: use sed -E instead of -r for better portability
scripts: frag2inc: use sed -E instead of -r for better portability

On systems where sed is not GNU sed, the script fails with an unknown
"-r" option error. Posix defines "-E" for the same purpose. Prefer the
later for portability.

Signed-off-by: Julien Olivain <e017b3aecfdd2dc1bdcf241eeb088a15ff1e3ada@free.fr>

jolivain/glslsandbox-player,jolivain/glslsandbox-player,jolivain/glslsandbox-player,jolivain/glslsandbox-player