Fix build with newer GCC.

Taken from upstream:

  https://sourceforge.net/p/libwpd/code/ci/333c8a26f231bea26ec3d56245315041bbf5577f/

--- a/src/lib/WPXTable.h
+++ b/src/lib/WPXTable.h
@@ -53,7 +53,7 @@
 	~WPXTable();
 	void insertRow();
 	void insertCell(unsigned char colSpan, unsigned char rowSpan, unsigned char borderBits);
-	const WPXTableCell  *getCell(size_t i, size_t j)
+	const WPXTableCell  *getCell(std::size_t i, std::size_t j)
 	{
 		return &(m_tableRows[i])[j];
 	}
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<div class='path'>path: <a href='/guix/log/?id=f8361ec8b5b8e0dc17d0f41e421ed791f15022b3'>root</a>/<a href='/guix/log/README?id=f8361ec8b5b8e0dc17d0f41e421ed791f15022b3'>README</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/README?id=f8361ec8b5b8e0dc17d0f41e421ed791f15022b3&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-05-20 01:58:04 +0200'>2021-05-20</span></td><td><a href='/guix/commit/README?id=c0087d33705f53cc3619a1a43a33602aaecc3a8b'>The #guix channel is hosted by Libera Chat.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Contact): Update network name.
* ROADMAP: Likewise.
* doc/contributing.texi (Contributing): Likewise.
* doc/guix.texi (After System Installation): Likewise.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-10-23 12:57:20 -0400'>2020-10-23</span></td><td><a href='/guix/commit/README?id=b5aaa3a4fb985d21e21e2a67f48b52f13ebd4728'>doc: Update README.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Installation): Do not mention installing Guix from Git anymore.
(Building from Git): Add section.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2020-10-22 22:47:54 -0400'>2020-10-22</span></td><td><a href='/guix/commit/README?id=503d2bfde08f9bf97bbf430516d2f19faedd4319'>README: Refer to the manual for building from Git.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Installing Guix from Guix): Remove section.
(Installation): For installing from Git, refer to the "Building from Git"
section of the manual and suggest using './pre-inst-env guix pull' rather than
'make install' for installing Guix.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2020-06-02 18:55:53 +0200'>2020-06-02</span></td><td><a href='/guix/commit/README?id=c75a80189fc19f6ff8b4c82d1d1801be6763b6d2'>doc: Update README to refer to the manual.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Requirements): Refer to the manual.
(Installation): Update URL of the manual.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-11-09 23:04:14 +0100'>2019-11-09</span></td><td><a href='/guix/commit/README?id=0758a70cc008171f31c848128deca9803536fe60'>doc: Mention value /var to localstatedir option.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Installing Guix from Guix): Mention value /var to localstatedir option.
* doc/contributing.texi (Building from Git): Likewise.
* doc/guix.texi (Requirements): Likewise.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>zimoun</td></tr>
<tr><td><span title='2019-09-04 23:41:07 +0200'>2019-09-04</span></td><td><a href='/guix/commit/README?id=f475c6e53e5b6912cc45663d50f1d03dadfb60b8'>doc: Update 'README'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README: Update intro a bit.
(Installing Guix as non-root): Remove as it's largely outdated.
(Contact): Update.
</span></span></td><td>Ludovic Courtès</td></tr>