Don't skip reading depend for 'make obj' unless it is alone.

This was effectively done in bsd.dep.mk quite some time ago.

MFC after:	2 weeks
Sponsored by:	Dell EMC

sys/conf/kern.post.mk

@@ -200,8 +200,9 @@ _meta_filemon=	1
 # Also skip generating or including .depend.* files if in meta+filemon mode
 # since it will track dependencies itself.  OBJS_DEPEND_GUESS is still used
 # for _meta_filemon but not for _SKIP_DEPEND.
-.if !defined(NO_SKIP_DEPEND) && (make(*obj) || \
+.if !defined(NO_SKIP_DEPEND) && \
     (!empty(.MAKEFLAGS:M-V) && empty(.MAKEFLAGS:M*DEP*)) || \
+    (${.TARGETS:M*obj} == ${.TARGETS} || \
     ${.TARGETS:M*clean*} == ${.TARGETS} || \
     ${.TARGETS:M*install*} == ${.TARGETS})
 _SKIP_DEPEND=	1