Add support for dynamic dependencies in ad hoc Buildscript recipes

Specifically, add the new `depdb dyndep` builtin that can be used to extract
dynamic dependencies from a program run or a file. For example:

obje{hello.o}: cxx{hello}
{{
  s = $path($<[0])

  depdb dyndep $cxx.poptions $cc.poptions --what=header --default-prereq-type=h -- $cxx.path $cxx.poptions $cc.poptions $cxx.mode -M -MG $s

  diag c++ ($<[0])

  o = $path($>)
  $cxx.path $cxx.poptions $cc.poptions $cc.coptions $cxx.coptions $cxx.mode -o $o -c $s
}}

Currently only the `make` dependency format is supported.

1 files changed, 98 insertions, 0 deletions

diff --git a/libbuild2/make-parser.test.testscript b/libbuild2/make-parser.test.testscript
new file mode 100644
index 0000000..6db00eb
--- /dev/null
+++ b/libbuild2/make-parser.test.testscript
@@ -0,0 +1,98 @@
+# file      : libbuild2/make-parser.test.testscript
+# license   : MIT; see accompanying LICENSE file
+
+: valid
+:
+$* <<EOI >>EOO
+  foo:
+
+  foo: bar
+
+  foo: bar baz
+
+  foo: bar \
+  baz
+
+  foo: bar\
+  baz
+
+  foo:\
+  bar baz\
+  fox
+
+  foo: bar \
+  \
+  baz
+
+  foo: bar\
+
+  foo bar: baz
+
+  foo \
+  bar: baz
+
+  foo \
+  bar \
+  : baz
+
+  \
+  foo: bar
+  EOI
+  T foo
+
+  T foo
+  P bar
+
+  T foo
+  P bar
+  P baz
+
+  T foo
+  P bar
+  P baz
+
+  T foo
+  P bar
+  P baz
+
+  T foo
+  P
+  P bar
+  P baz
+  P fox
+
+  T foo
+  P bar
+  P
+  P baz
+
+  T foo
+  P bar
+  P
+
+  T foo
+  T bar
+  P baz
+
+  T foo
+  T bar
+  P baz
+
+  T foo
+  T bar
+  T
+  P baz
+
+  T
+  T foo
+  P bar
+  EOO
+
+: lax
+:
+$* <<EOI >>EOO
+  foo: c:\tmp\bar
+  EOI
+  T foo
+  P c:\tmp\bar
+  EOO