depgen: Do not perform dependency generation within templates

This makes me slightly uncomfortable because I haven't researched why
exactly this was not a problem before.  We encountered this issue using an
inline template iterating over the symbol table yielding a `c:value-of',
which is admittedly something that we haven't done before.

Hopefully it's an isolated case.

I diffed the offending object file and the entire linked tax calculator and
they were bit-for-bit identical, so we're probably good.

* src/current/include/depgen.xsl (preproc:depgen): Do not perform dependency
    generation within templates.

src/current/include/depgen.xsl

@@ -357,6 +357,11 @@
 </xsl:template>
 
 
+<xsl:template match="c:*[ ancestor::lv:template ]"
+              mode="preproc:depgen" priority="8">
+  <!-- ignore symbols within templates -->
+</xsl:template>
+
 <xsl:template name="preproc:depgen-c-normal" match="c:value-of|c:when" mode="preproc:depgen" priority="5">
   <xsl:param name="name" select="@name" />
   <xsl:variable name="pkg" as="element( lv:package )"