rpm: Handle proper return value to avoid major issues

0001-rpm-rpmio.c-restrict-virtual-memory-usage-if-limit-s.patch changed
to avoid critical issues
Handled return values of getrlimit() and lzma_cputhreads() functions
to avoid unexpected behaviours like devide by zero and potential read
of uninitialized variable 'virtual_memory'
Upstream-Status: Pending [merge of multithreading patches to upstream]

Signed-off-by: Ranjitsinh Rathod <ranjitsinh.rathod@kpit.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>