Re: Regression with large XML data input

> The whitespace can be preserved by setting xmlKeepBlanksDefault before
> parsing.  See attached v2.  That function is deprecated, though.  But
> libxml2 uses thread-local globals, so it should be safe.  Other than
> that, I see no other way to set XML_PARSE_NOBLANKS with
> xmlParseBalancedChunkMemory.
> 
> [1] https://gitlab.gnome.org/GNOME/libxml2/-/blob/408bd0e18e6ddba5d18e51d52da0f7b3ca1b4421/parserInternals.c#L2833

Hi everyone, 

I have a small issue that needs resolving.

My environment:
```
postgres@zxm-VMware-Virtual-Platform:~$ uname -i -s -r -v
Linux 6.11.0-29-generic #29-Ubuntu SMP PREEMPT_DYNAMIC Fri Jun 13 20:29:41 UTC 2025 x86_64
postgres@zxm-VMware-Virtual-Platform:~$ 
postgres@zxm-VMware-Virtual-Platform:~$ xml2-config --version 
2.12.7
```

After setting COPT=-Werror, compilation fails with the following errors (warnings are enforced as errors):
```
xml.c: In function ‘xml_parse’:
xml.c:1919:25: error: ‘xmlKeepBlanksDefault’ is deprecated [-Werror=deprecated-declarations]
 1919 |                         save_keep_blanks = xmlKeepBlanksDefault(preserve_whitespace ? 1 : 0);
      |                         ^~~~~~~~~~~~~~~~
In file included from xml.c:51:
/usr/include/libxml2/libxml/parser.h:957:17: note: declared here
  957 |                 xmlKeepBlanksDefault    (int val);
      |                 ^~~~~~~~~~~~~~~~~~~~
xml.c:1943:25: error: ‘xmlKeepBlanksDefault’ is deprecated [-Werror=deprecated-declarations]
 1943 |                         xmlKeepBlanksDefault(save_keep_blanks);
      |                         ^~~~~~~~~~~~~~~~~~~~
/usr/include/libxml2/libxml/parser.h:957:17: note: declared here
  957 |                 xmlKeepBlanksDefault    (int val);
      |                 ^~~~~~~~~~~~~~~~~~~~
xml.c:1956:17: error: ‘xmlKeepBlanksDefault’ is deprecated [-Werror=deprecated-declarations]
 1956 |                 xmlKeepBlanksDefault(save_keep_blanks);
      |                 ^~~~~~~~~~~~~~~~~~~~
/usr/include/libxml2/libxml/parser.h:957:17: note: declared here
  957 |                 xmlKeepBlanksDefault    (int val);
      |                 ^~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
```

These deprecation warnings do not impact the test results in any way. 
Therefore, I have attached a patch to suppress these specific warnings. 

--
Regards,
Man Zeng
www.openhalo.org