sb: Improve the error handling for setbuilder errors.

If an error happens in the setbuilder code report the error. Errors
in the build phase are logged in the RSB Error Report.
sb: Tighten the canadian cross compile detection.

A canadian cross compile needs the build, host and target being
different.

Clean up the error handling.
sb: Add support for building RTEMS 3rd party packages.

Remove the 'opt' from various macros and shell variables.

Add pkgconfig to the checks to make it clear the check is a
pkgconfig check.

Add NTP support as the first package to be built using the RSB.

Split the RTEMS URL's out from the base bset file into a separate
file that be included by other files.

Add an RTEMS BSP configuration file to help abstract the process
of building 3rd party packages.

Clean the cross and canadian cross support up so we can cleanly support
cross and canadian cross building.

Refactor the pkgconfig support and clean up the PC file handling of
loading modules.

Add support for %{?..} to return false if a macro is %{nil}.

Add %{pkgconfig ..} support to allow better control of access RTEMS
pkgconfig files.
config: Use the prefix as the tools path if no --with-tools.

To use tools not in the installed RTEMS path use --with-tools. If
the --with-tools option is not supplied use the --prefix path.
config: NTP build fails with too many jobs.

Do not use any jobs to build NTP.