applied patch from Patrick Welche provided in bug #125432 , future

* libxml.m4: applied patch from Patrick Welche provided in
  bug #125432 , future proofing the .m4 file.
* parser.c: resetting the context should also reset the error
* TODO: problem of conformance w.r.t. E20 was raised in the
  XML Core telconf and libxml2 isn't conformant there.
Daniel
diff --git a/libxml.m4 b/libxml.m4
index afffd39..4655dca 100644
--- a/libxml.m4
+++ b/libxml.m4
@@ -7,7 +7,7 @@
 dnl AM_PATH_XML([MINIMUM-VERSION, [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]]])
 dnl Test for XML, and define XML_CFLAGS and XML_LIBS
 dnl
-AC_DEFUN(AM_PATH_XML,[ 
+AC_DEFUN([AM_PATH_XML],[ 
 AC_ARG_WITH(xml-prefix,
             [  --with-xml-prefix=PFX   Prefix where libxml is installed (optional)],
             xml_config_prefix="$withval", xml_config_prefix="")
@@ -202,7 +202,7 @@
 dnl AM_PATH_XML2([MINIMUM-VERSION, [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]]])
 dnl Test for XML, and define XML_CFLAGS and XML_LIBS
 dnl
-AC_DEFUN(AM_PATH_XML2,[ 
+AC_DEFUN([AM_PATH_XML2],[ 
 AC_ARG_WITH(xml-prefix,
             [  --with-xml-prefix=PFX   Prefix where libxml is installed (optional)],
             xml_config_prefix="$withval", xml_config_prefix="")