[libxslt] Adjust expected error output for libxml2 changes

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 42f5378a0a8dee89a51aefc5a05446d3a99ec756
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Fri Sep 29 13:11:26 2017 +0200

    Adjust expected error output for libxml2 changes

 tests/general/bug-165.err |    1 +
 tests/general/bug-180.err |    1 +
 tests/general/bug-184.err |    1 +
 tests/general/bug-194.err |    2 ++
 4 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/tests/general/bug-165.err b/tests/general/bug-165.err
index 490fe53..dab9d7e 100644
--- a/tests/general/bug-165.err
+++ b/tests/general/bug-165.err
@@ -1,5 +1,6 @@
 runtime error: file ./bug-165.xsl line 6 element value-of
 Variable 'pStyle' has not been declared.
+XPath error : Undefined variable
 runtime error: file ./bug-165.xsl line 6 element value-of
 XPath evaluation returned no result.
 no result for ./../docs/bug-165.xml
diff --git a/tests/general/bug-180.err b/tests/general/bug-180.err
index 6dd9bb2..7b15044 100644
--- a/tests/general/bug-180.err
+++ b/tests/general/bug-180.err
@@ -1,3 +1,4 @@
 runtime error: file ./bug-180.xsl line 4 element copy-of
 Variable 'xxx' has not been declared.
+XPath error : Undefined variable
 no result for ./../docs/bug-180.xml
diff --git a/tests/general/bug-184.err b/tests/general/bug-184.err
index 9f029c9..eaeb65b 100644
--- a/tests/general/bug-184.err
+++ b/tests/general/bug-184.err
@@ -1,5 +1,6 @@
 runtime error: file ./bug-184.xsl line 5 element value-of
 Variable 'nonexistent' has not been declared.
+XPath error : Undefined variable
 runtime error: file ./bug-184.xsl line 5 element value-of
 XPath evaluation returned no result.
 no result for ./../docs/bug-184.xml
diff --git a/tests/general/bug-194.err b/tests/general/bug-194.err
index 3e1e3d3..2d5a6be 100644
--- a/tests/general/bug-194.err
+++ b/tests/general/bug-194.err
@@ -1,7 +1,9 @@
 runtime error
 Variable 'p' has not been declared.
+XPath error : Undefined variable
 runtime error: file ./bug-194.xsl line 4 element param
 Failed to evaluate the expression of variable 'p'.
+XPath error : Undefined variable
 runtime error: file ./bug-194.xsl line 5 element param
 Failed to evaluate the expression of variable 'p2'.
 no result for ./../docs/bug-194.xml