rrdtool: fix do_configure failure on some hosts

On some hosts, when building rrdtool, we would meet do_configure error like
below.

| *** Module name IN: /usr/lib64/perl/5.22.0/POSIX.pm
| *** p1: /usr/lib64/  p3: perl/5.22.0/  p5: POSIX.pm
| *** Module name OUT: /path/to/builddir/tmp/sysroots/x86_64-linux/usr/lib/perl-native/perl/5.22.1/POSIX.pm
| POSIX object version 1.53_01 does not match $POSIX::VERSION 1.53 at /usr/lib64/perl/5.22.0/XSLoader.pm line 108.

Set PERLHOSTLIB to "" to fix the above error.

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Armin Kuster <akuster808@gmail.com>