no 'object' file generated ?

Anyone know why Jenkins sometimes throws this error?

C:/cygwin/home/tdf/lode/jenkins/workspace/lo_gerrit_master/Gerrit/Gerrit/Platform/Windows/shell/source/win32/shlxthandler/util/utilities.cxx(110)
: error C2220: warning treated as error - no 'object' file generated


I can't find any other failures in the output.
That was on Windows. In the same build[*], but on Linux, I have this:

nsinstall: cannot access nss.h: No such file or directory
../../coreconf/rules.mk:752: recipe for target 'export' failed
make[4]: *** [export] Aborted


Any ideas? How can we fix/avoid this?

Thanks!

[*] http://ci.libreoffice.org/job/lo_gerrit_master/419/