nspr: remove unnecessary files from the main package

This patch does the following:
 * removes compile-et.pl and prerr.properties from the main package
   because these files are needed only at compile time;
 * moves nspr-config script to nspr-dev package where it belongs;
 * adds 'perl' RDEPENDS for nspr-dev since the package contains a perl
   script for running some tests;

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>