xml: Restrict `<loc>` transform to under `<pinlocations>`.

Signed-off-by: Tim 'mithro' Ansell <me@mith.ro>

composable-loc-implicit-parent.golden.xml

diff --git a/composable-loc-implicit-parent.golden.xml b/composable-loc-implicit-parent.golden.xml
index 0f993d1..f6a4899 100644
--- a/composable-loc-implicit-parent.golden.xml
+++ b/composable-loc-implicit-parent.golden.xml
@@ -2,10 +2,17 @@
 <xml>
   <pb_type name="parent">
     <input name="i" width="2"/>
-    <loc>
-      parent.o
-      parent.i[0]
-      parent.i[1]
-    </loc>
+    <pinlocations>
+      <loc>
+        parent.o
+        parent.i[0]
+        parent.i[1]
+      </loc>
+    </pinlocations>
+    <random>
+      <loc>
+        <port name="o"/>
+      </loc>
+    </random>
   </pb_type>
 </xml>

composable-loc-implicit-parent.xml

diff --git a/composable-loc-implicit-parent.xml b/composable-loc-implicit-parent.xml
index 9440379..e8bc8d2 100644
--- a/composable-loc-implicit-parent.xml
+++ b/composable-loc-implicit-parent.xml
@@ -8,10 +8,17 @@
 <xml>
  <pb_type name="parent">
   <input name="i" width="2" />
-  <loc>
-   <port name="o" />
-   <port name="i" bit="0" />
-   <port name="i" bit="1" />
-  </loc>
+  <pinlocations>
+   <loc>
+    <port name="o" />
+    <port name="i" bit="0" />
+    <port name="i" bit="1" />
+   </loc>
+  </pinlocations>
+  <random>
+   <loc>
+    <port name="o" />
+   </loc>
+  </random>
  </pb_type>
 </xml>