afterstep: flagged NOPARALLEL

Note:

Running parallel make jobs seems to be unreliable while build afterstep.
It also seems to behave slightly different when ccache is enabled for
the build, and the issue was actually discovered with ccache disabled.

afterstep/afterstep/afterstep.desc

@@ -31,6 +31,8 @@
 
 [C] extra/windowmanager
 
+[F] NOPARALLEL
+
 [L] GPL
 [S] Stable
 [V] 2.2.11