msxml3: Handle libxml2 API breakage.

[Thomas Faber]

---
v2.9.8 adds 'const' to the callback function signatures, which causes
warnings such as:

schema.c: In function ‘cache_add_entry’:
schema.c:1008:47: error: passing argument 3 of ‘xmlHashRemoveEntry’ from incompatible pointer type [-Werror=incompatible-pointer-types]
     if (xmlHashRemoveEntry(cache->cache, uri, cache_free))
                                               ^~~~~~~~~~
In file included from /usr/include/libxml2/libxml/parser.h:18,
                 from /usr/include/libxml2/libxml/xmlerror.h:10,
                 from schema.c:29:
/usr/include/libxml2/libxml/hash.h:160:47: note: expected ‘xmlHashDeallocator’ {aka ‘void (*)(void *, const unsigned char *)’} but argument is of type ‘void (*)(void *, xmlChar *)’ {aka ‘void (*)(void *, unsigned char *)’}
                            xmlHashDeallocator f);
                            ~~~~~~~~~~~~~~~~~~~^

This isn't the prettiest solution, but I think it's better than casting
the function pointers. Happy to take ideas to make it nicer.


 dlls/msxml3/schema.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/dlls/msxml3/schema.c b/dlls/msxml3/schema.c
index 80879852041a..e385b9b56357 100644
--- a/dlls/msxml3/schema.c
+++ b/dlls/msxml3/schema.c
@@ -52,6 +52,12 @@
 
 WINE_DEFAULT_DEBUG_CHANNEL(msxml);
 
+#if LIBXML_VERSION >= 20908
+#define XMLHASH_CONST const
+#else
+#define XMLHASH_CONST
+#endif
+
 /* We use a chained hashtable, which can hold any number of schemas
  * TODO: grow/shrink hashtable depending on load factor
  * TODO: implement read-only where appropriate
@@ -980,7 +986,7 @@ static cache_entry* cache_entry_from_url(VARIANT url, xmlChar const* nsURI, MSXM
     return entry;
 }
 
-static void cache_free(void* data, xmlChar* name /* ignored */)
+static void cache_free(void* data, XMLHASH_CONST xmlChar* name /* ignored */)
 {
     cache_entry_release((cache_entry*)data);
 }
@@ -1397,7 +1403,7 @@ static HRESULT WINAPI schema_cache_get_namespaceURI(IXMLDOMSchemaCollection2* if
     return S_OK;
 }
 
-static void cache_copy(void* data, void* dest, xmlChar* name)
+static void cache_copy(void* data, void* dest, XMLHASH_CONST xmlChar* name)
 {
     schema_cache* This = (schema_cache*) dest;
     cache_entry* entry = (cache_entry*) data;
-- 
2.20.1