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, 0 deletions

diff --git a/unit-tests/deptgt.mk b/unit-tests/deptgt.mk
new file mode 100644
index 000000000000..add21dc0baee
--- /dev/null
+++ b/unit-tests/deptgt.mk
@@ -0,0 +1,9 @@
+# $NetBSD: deptgt.mk,v 1.2 2020/08/16 14:25:16 rillig Exp $
+#
+# Tests for special targets like .BEGIN or .SUFFIXES in dependency
+# declarations.
+
+# TODO: Implementation
+
+all:
+	@:;