macros: use smp_mflags

to avoid embedding the number of CPU cores
in the .src.rpm header's expanded SPEC field.

See also rpm-software-management/rpm#2343

This patch was done while working on reproducible builds for openSUSE.

Author: bmwiedemann

data/macros.meson

@@ -28,7 +28,7 @@
 %meson_build \
     %{shrink:%{__meson} compile \
         -C %{_vpath_builddir} \
-        -j %{_smp_build_ncpus} \
+        %{_smp_mflags} \
         %{?__meson_verbose:--verbose} \
         %{nil}}