./configure in psmisc 22.6 tested for a working C++ compiler and errored out
if not found, even though psmisc doesn't need it - Fixed in 22.8.

pstree.c uses __progname for pstree.x11 support, which isn't (per default)
available in uclibc. This stuff isn't really critical, so just disable it.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>