Add %make_build macro for hiding parallel-build magic from specs (tic…

…ket #115)

- This allows simplifying the make invokations from specs. In particular
  the parallel build options no longer need to be messed with from specs,
  and %__make can be overridden to force a different make implementation
  to be used throughout the spec.
- While a lot of software builds correctly in parallel, there are always
  exceptions... together with _smp_ncpus_max macro this can now be
  expressed with a separate "%global _smp_ncpus_max 1" (or any other
  arbitrary value beyond which parallel build is buggy) line which
  is easy to grep for and experiment with.

macros.in

@@ -860,6 +860,10 @@ package or when debugging this package.\
 	--mandir=%{_mandir} \\\
 	--infodir=%{_infodir}
 
+#------------------------------------------------------------------------------
+# The "make" analogue, hiding the _smp_mflags magic from specs
+%make_build %{__make} %{?_smp_mflags}
+
 #------------------------------------------------------------------------------
 # The make install analogue of %configure for modern autotools:
 %make_install %{__make} install DESTDIR=%{?buildroot}