revamped the elfgcchack.h format to cope with gcc4 change of aliasing

* doc/apibuild.py doc/elfgcchack.xsl: revamped the elfgcchack.h
  format to cope with gcc4 change of aliasing allowed scopes, had
  to add extra informations to doc/libxml2-api.xml to separate
  the header from the c module source.
* *.c: updated all c library files to add a #define bottom_xxx
  and reimport elfgcchack.h thereafter, and a bit of cleanups.
* doc//* testapi.c: regenerated when rebuilding the API
Daniel
diff --git a/doc/APIconstructors.html b/doc/APIconstructors.html
index 9372c05..a65bd61 100644
--- a/doc/APIconstructors.html
+++ b/doc/APIconstructors.html
@@ -484,6 +484,7 @@
 </p><h2>Type xmlSchemaValPtr:</h2><p><a href="html/libxml-xmlschemastypes.html#xmlSchemaCopyValue">xmlSchemaCopyValue</a><br />
 <a href="html/libxml-xmlschemastypes.html#xmlSchemaNewNOTATIONValue">xmlSchemaNewNOTATIONValue</a><br />
 <a href="html/libxml-xmlschemastypes.html#xmlSchemaNewStringValue">xmlSchemaNewStringValue</a><br />
+</p><h2>Type xmlSchemaValType:</h2><p><a href="html/libxml-xmlschemastypes.html#xmlSchemaGetValType">xmlSchemaGetValType</a><br />
 </p><h2>Type xmlSchemaValidCtxtPtr:</h2><p><a href="html/libxml-xmlschemas.html#xmlSchemaNewValidCtxt">xmlSchemaNewValidCtxt</a><br />
 </p><h2>Type xmlStreamCtxtPtr:</h2><p><a href="html/libxml-pattern.html#xmlPatternGetStreamCtxt">xmlPatternGetStreamCtxt</a><br />
 </p><h2>Type xmlTextReaderPtr:</h2><p><a href="html/libxml-xmlreader.html#xmlNewTextReader">xmlNewTextReader</a><br />