register xmlSchemaSetValidErrors, patch from Brent Hendricks in the

* python/libxml.c: register xmlSchemaSetValidErrors, patch from
  Brent Hendricks in the mailing-list
* include/libxml/valid.h HTMLparser.c SAX2.c valid.c
  parserInternals.c: fix #156626 and more generally how to find out
  if a validation contect is part of a parsing context or not. This
  can probably be improved to make 100% sure that vctxt->userData
  is the parser context too. It's a bit hairy because we can't
  change the xmlValidCtxt structure without breaking the ABI since
  this change xmlParserCtxt information indexes.
Daniel
diff --git a/configure.in b/configure.in
index 64a6c0e..ed6b94c 100644
--- a/configure.in
+++ b/configure.in
@@ -446,7 +446,9 @@
 	    with_docbook="yes"
 	fi
     fi
+    if test "${CC}" = "gcc" ; then
     CFLAGS="-g -O -pedantic -W -Wunused -Wimplicit -Wreturn-type -Wswitch -Wcomment -Wtrigraphs -Wformat -Wchar-subscripts -Wuninitialized -Wparentheses -Wshadow -Wpointer-arith -Wcast-align -Wwrite-strings -Waggregate-return -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline -Wredundant-decls -Wall"
+    fi
     STATIC_BINARIES="-static"
 dnl -Wcast-qual -ansi
 else