liblog4c-localtime: fix linking error without pthread

Fixes http://autobuild.buildroot.net/results/34f/34f238cdb1b1b4be1a11143b5e4a17c78c2fc289/



The rollingfile functionality only gets built if pthread support is
available, but a call to these functions from log4c_fini() was outside
the #if WITH_ROLLINGFILE conditional, causing linker errors when the
library is used.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>