rpm: make -ql display more compatible; improve help text

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
rpm: use "create+rename" method of replacing existing files

Users were reporting getting errors like
"ls: error while loading shared libraries: libc.so.6: ELF load command past end of file"
while rpm was unpacking glibc tarball.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
rpm: stop using statics; move main() to the end of the source file

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
rpm: unmap rpm file before working with next one

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>