This patch scales all dash patterns of the postscript and svg terminal with the current linewidth. To test, use e.g.:
#set terminal postscript eps; ext='eps'
set terminal svg standalone; ext='svg'
set output 'dashlength-1.'.ext
set termoption dashlength 1
plot x dt 2, 2*x dt 2 lw 5, 3*x dt '.-', 4*x dt '.-' lw 5
set output 'dashlength-3.'.ext
set termoption dashlength 3
replot
This also uses the dl1 and dl2 procedures for the custom dash patterns in the postscript terminal, like they are used for the built-in dash patterns.
