libdpkg: Do not fallback to strlen() when using strcspn()

The strcspn() function always returns the requested length, there is no
need to fallback to strlen().

lib/dpkg/pkg-format.c

@@ -294,8 +294,6 @@ virt_source_package(struct varbuf *vb,
 		name = pkg->set->name;
 
 	len = strcspn(name, " ");
-	if (len == 0)
-		len = strlen(name);
 
 	varbuf_add_buf(vb, name, len);
 }
@@ -319,8 +317,6 @@ virt_source_version(struct varbuf *vb,
 		version++;
 
 		len = strcspn(version, ")");
-		if (len == 0)
-			len = strlen(version);
 
 		varbuf_add_buf(vb, version, len);
 	}

lib/dpkg/pkg-show.c

@@ -131,20 +131,15 @@ pkg_name(struct pkginfo *pkg, enum pkg_name_arch_when pnaw)
 }
 
 const char *
-pkg_summary(const struct pkginfo *pkg, const struct pkgbin *pkgbin, int *len_ret)
+pkg_summary(const struct pkginfo *pkg, const struct pkgbin *pkgbin, int *len)
 {
 	const char *pdesc;
-	size_t len;
 
 	pdesc = pkgbin->description;
 	if (!pdesc)
 		pdesc = _("(no description available)");
 
-	len = strcspn(pdesc, "\n");
-	if (len == 0)
-		len = strlen(pdesc);
-
-	*len_ret = len;
+	*len = strcspn(pdesc, "\n");
 
 	return pdesc;
 }