buildrpm: move creation of RPM directories from dockerrpm

Handling the creation of the RPM directories in buildrpm
is more consistent and takes care of non-docker builds as well.

contrib/buildrpm

@@ -68,7 +68,7 b' else'
     RPMPYTHONVER=%{nil}
 fi
 
-mkdir -p $RPMBUILDDIR/SOURCES
+mkdir -p $RPMBUILDDIR/{SOURCES,BUILD,SRPMS,RPMS}
 $HG archive -t tgz $RPMBUILDDIR/SOURCES/mercurial-$version-$release.tar.gz
 if [ "$PYTHONVER" ]; then
 (

contrib/dockerrpm

@@ -15,8 +15,6 b' initcontainer $PLATFORM'
 RPMBUILDDIR=$ROOTDIR/packages/$PLATFORM
 contrib/buildrpm --rpmbuilddir $RPMBUILDDIR --prepare $*
 
-mkdir -p $RPMBUILDDIR/{BUILD,SRPMS,RPMS}
-
 DSHARED=/mnt/shared
 $DOCKER run -u $DBUILDUSER --rm -v $RPMBUILDDIR:$DSHARED $CONTAINER \
     rpmbuild --define "_topdir $DSHARED" -ba $DSHARED/SPECS/mercurial.spec --clean