package_rpm.bbclass: added from Poky

package_rpm.bbclass: added from Poky

Squashed changes from Poky:

svn r5067 - package_rpm.bbclass: Update against recent packaging changes
            and start to implement dependency handling.
svn r5100 - package_rpm.bbclass: Fix empty package handling, handle
	    package dependency renaming by adding a missing function
	    call and expand RPMBUILD before changing the dictonary so
	    local PV/PR changes don't break the WORKDIR variable
	    expansion
svn r5111 - package_rpm.bbclass: Stop autogenerated dependencies for
            now, its not functioning correctly
svn r5116 - package_rpm.bbclass: files needs to start from /
svn r5129 - package_rpm.bbclass: Fix problems with package version with
            '-' in the version (replace with '+'), improve the Requires
	    and Recommends generation code
svn r5131 - package_rpm.bbclass: Add support for postinst and preinst scripts
svn r5381 - classes: Split rpm feeds by PACKAGE_ARCH
svn r5390 - package_rpm.bbclass: Improve handling of '-' characters in Requires
            and Recommends fields
svn r5393 - package_rpm.bbclass: Fix package version fixing for PKG renamed packages
svn r5397 - package_rpm.bbclass: Fix dependency rebuilding bug
svn r5413 - package_rpm.bbclass: save value of RPMBUILDPATH as it is needed for
            packaging

package_rpm.bbclass: Don't use the system wide RPM macros.

This fixes the build on Fedora 10 where the RPM system macros obliterate
the value of BuildRoot that is set in the spec file.

package_rpm.bbclass: fix indentation package_rpm.bbclass: fix syntax errors
package_rpm.bbclass: save RPROVIDES in packages