small typo pointed out by Mike Hommey slightly improved the --c14n

* xmlIO.c: small typo pointed out by Mike Hommey
* doc/xmllint.xml, xmllint.html, xmllint.1: slightly improved
  the --c14n description, c.f. #144675 .
* nanohttp.c nanoftp.c: applied a first simple patch from
  Mike Hommey for $no_proxy, c.f. #133470
* parserInternals.c include/libxml/parserInternals.h
  include/libxml/xmlerror.h: cleanup to avoid 'error' identifier
  in includes #
* parser.c SAX2.c debugXML.c include/libxml/parser.h:
  first version of the inplementation of parsing within
  the context of a node in the tree #142359, new function
  xmlParseInNodeContext(), added support at the xmllint --shell
  level as the "set" function
* test/scripts/set* result/scripts/* Makefile.am: extended
  the script based regression tests to instrument the new function.
Daniel
diff --git a/valid.c b/valid.c
index ade90dd..15514d8 100644
--- a/valid.c
+++ b/valid.c
@@ -18,6 +18,7 @@
 
 #include <libxml/xmlmemory.h>
 #include <libxml/hash.h>
+#include <libxml/uri.h>
 #include <libxml/valid.h>
 #include <libxml/parser.h>
 #include <libxml/parserInternals.h>