Allow usage when fork() is not available
When fork() is not available, we need to define NO_ZPIPE so that libXpm doesn't try to fork/exec to use a pipe to uncompress compressed .xpm files. There is obviously a loss of functionality, but loading uncompressed .xpm files should continue to work.
Signed-off-by: Thomas Petazzoni email@example.com
Signed-off-by: Fabrice Fontaine firstname.lastname@example.org