error: 'ARG_MAX' undeclared

wapi_glob.c: In function 'globextend':
wapi_glob.c:303: error: 'ARG_MAX' undeclared (first use in this function)
wapi_glob.c:303: error: (Each undeclared identifier is reported only once
wapi_glob.c:303: error: for each function it appears in.)
make[3]: *** [wapi_glob.lo] Error 1
make[3]: Leaving directory `/home/test/checkout/gnome2/mono-1.2.6/mono/io-layer'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/home/test/checkout/gnome2/mono-1.2.6/mono'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/test/checkout/gnome2/mono-1.2.6'
make: *** [all] Error 2

Caused by having a newer glibc. Fixed in Mono SVN (Mono 2.0 should be out end of Sept 2008). Until then, you should update your copy of jhbuild and it will patch the mono sources to fix this.