build_rpm.sh: set --build to guess for Darwin

Darwin platform is not RPM based, thus by default on Darwin we
pick 'quess' option to figure out system triplet. For other targets
default is 'auto', which assumes RPM based Linux distribution and
fetches system triplet from RPM directly.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
build_rpm.sh: bump zlib version to 1.2.8

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
build_rpm.sh: enable 64-bit for NSS and NSPR for Xeon Phi

We set 64-bit builds based on *_amd64_*, yet for Xeon Phi currently
we use *_mic_* in architecture triplet.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Fix multiple identical check-* tasks.

- Add a check to serial() for double job as in parallel().
- Fix issue where we check for top level package N times, instead
  of checking each dependency, i.e., packages we need to build.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Allow incremental/continued build with --no-bootstrap option

The old scheduler allowed building everything in one step, but
functionality was lost with new scheduler. rpmCacheUpdate() with
--no-bootstrap option yields an empty RPM DB cache. While preparing
tasks in checkPackageInCache() we also add install-* tasks as
dependencies, yet such install tasks are never queued and scheduler
goes into a loop waiting for non-existent tasks to finish.
isPackageInstalled() due to empty RPM DB cache fails to report that
some or all packages are already installed. Update isPackageInstalled()
to check for .package-checksum file if --no-bootstrap option is
enabled.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #23 from davidlt/V00-22-XX

[V00-22-XX] Misc. bugfixes and updates