[libxslt] Adjust error message in expected test output

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 63e276800eaaedd007c50c23a8f383736beb3e7c
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Mon Apr 8 15:01:18 2019 +0200

    Adjust error message in expected test output
    
    XPath error messages changed after a recent libxml2 commit. The root
    cause is that func:function doesn't signal errors to the XPath engine
    which should be fixed.

 tests/general/bug-201.err | 2 +-
 tests/general/bug-215.err | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/tests/general/bug-201.err b/tests/general/bug-201.err
index 775c4cf7..a115d4d2 100644
--- a/tests/general/bug-201.err
+++ b/tests/general/bug-201.err
@@ -1,6 +1,6 @@
 runtime error: file ./bug-201.xsl line 13 element copy-of
 exsltFuncFunctionFunction: Potentially infinite recursion detected in function {test}func.
-xmlXPathCompiledEval: No result on the stack.
+XPath error : Stack usage error
 runtime error: file ./bug-201.xsl line 8 element param
 Failed to evaluate the expression of variable 'var'.
 no result for ./../docs/bug-201.xml
diff --git a/tests/general/bug-215.err b/tests/general/bug-215.err
index a4fbd23d..86556144 100644
--- a/tests/general/bug-215.err
+++ b/tests/general/bug-215.err
@@ -2,7 +2,7 @@
 element fake: error : Node has no parent
     ELEMENT elem
 {DEF}f: cannot write to result tree while executing a function
-xmlXPathCompiledEval: No result on the stack.
+XPath error : Stack usage error
 runtime error: file ./bug-215.xsl line 5 element variable
 Evaluating global variable  var/param being computed failed
 no result for ./../docs/bug-215.xml