Import bmake-20200902vendor/NetBSD/bmake/20200902

Lots of code refactoring, simplification and cleanup.
Lots of new unit-tests providing much higher code coverage.
All courtesy of rillig at netbsd.

Other significant changes:

o new read-only variable .SHELL which provides the path of the shell
  used to run scripts (as defined by  the .SHELL target).

o new debug option -dl: LINT mode, does the equivalent of := for all
  variable assignments so that file and line number are reported for
  variable parse errors.

1 files changed, 9 insertions, 5 deletions

diff --git a/mk/init.mk b/mk/init.mk
index d4ae45372d9c..0dae997beb54 100644
--- a/mk/init.mk
+++ b/mk/init.mk
@@ -1,14 +1,14 @@
-# $Id: init.mk,v 1.17 2020/05/25 20:15:07 sjg Exp $
+# $Id: init.mk,v 1.21 2020/08/19 17:51:53 sjg Exp $
 #
 #	@(#) Copyright (c) 2002, Simon J. Gerraty
 #
 #	This file is provided in the hope that it will
 #	be of use.  There is absolutely NO WARRANTY.
 #	Permission to copy, redistribute or otherwise
-#	use this file is hereby granted provided that 
+#	use this file is hereby granted provided that
 #	the above copyright notice and this notice are
-#	left intact. 
-#      
+#	left intact.
+#
 #	Please send copies of changes and bug-fixes to:
 #	sjg@crufty.net
 #
@@ -65,7 +65,11 @@ CC_PIC?= -DPIC
 CXX_PIC?= ${CC_PIC}
 PROFFLAGS?= -DGPROF -DPROF
 
-.if ${.MAKE.LEVEL:U1} == 0 && ${BUILD_AT_LEVEL0:Uyes:tl} == "no"
+# targets  that are ok  at level 0
+LEVEL0_TARGETS += clean* destory*
+M_ListToSkip= O:u:S,^,N,:ts:
+
+.if ${.MAKE.LEVEL:U1} == 0 && ${MK_DIRDEPS_BUILD:Uno} == "yes" && ${.TARGETS:Uall:${LEVEL0_TARGETS:${M_ListToSkip}}} != ""
 # this tells lib.mk and prog.mk to not actually build anything
 _SKIP_BUILD = not building at level 0
 .endif