src/current/pkg-dep.xsl: Recognize step-level imports

First thing to note: this belong in liza-proguic, not here.  But it's here
right now, so for now I'm making the change.  The relationship between TAME
and proguic is awkward and will hopefully be improved upon in the near
future.

As for this actual change: step-level fragments will be concatenated such
that the imports will appear at the step level rather than the root.

RELEASES.md

@@ -26,6 +26,8 @@ Build System
 - `configure` will no longer immediately generate `suppliers.mk`.
   - Additionally, `build-aux/suppmk-gen`, which `configure` directly invoked
     until now, was removed in favor of generic rules in `Makefile.am`.
+- Step-level imports in program definitions are now recognized to
+  accommodate liza-proguic's step-level package generation.
 
 
 v17.7.0 (2020-12-09)

src/current/pkg-dep.xsl

@@ -42,9 +42,9 @@
   </xsl:for-each>
 </xsl:template>
 
-<xsl:template match="lvp:program">
+<xsl:template match="lvp:program|lvp:program-fragment">
   <!-- output deps, one per line -->
-  <xsl:for-each select="lvp:import[ @package ]">
+  <xsl:for-each select="( . | lvp:step )/lvp:import[ @package ]">
     <xsl:value-of select="concat( @package, $nl )" />
   </xsl:for-each>
 </xsl:template>