Get rid of "blanks wrapper" for parameter entities

Now that replacement of parameter entities goes exclusively through
xmlSkipBlankChars, we can account for the surrounding space characters
there and remove the "blanks wrapper" hack.
diff --git a/result/errors10/781205.xml.err b/result/errors10/781205.xml.err
index f6395d6..3ddc203 100644
--- a/result/errors10/781205.xml.err
+++ b/result/errors10/781205.xml.err
@@ -1,7 +1,7 @@
-Entity: line 1: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
+./test/errors10/781205.xml:3: parser error : internal error: xmlParseInternalSubset: error detected in Markup declaration
 
- %a; 
-    ^
+  %a;
+     ^
 Entity: line 1: 
 <:0000
 ^