LibreOffice: drop --with-theme= and add back --with-distro=... (#2665)

It seems we can't pass "breeze sifr" as arguments to --with-theme
from the recipe, so add back the --with-distro=LibreOfficeHaiku
and let autogen.sh find in distro-configs/LibreOfficeHaiku.conf
the "--with-theme=breeze sifr" parameter as it did previously.

app-office/libreoffice/libreoffice-6.2.0.0~git.recipe

@@ -202,6 +202,7 @@ BUILD()
 	ln -s core core-$COMMIT; cd core
 
 	runConfigure ./autogen.sh \
+		--with-distro=LibreOfficeHaiku \
 		--enable-qt5 \
 		--enable-release-build \
 		--enable-readonly-installset \
@@ -268,7 +269,6 @@ BUILD()
 		--with-system-poppler \
 		--with-system-redland \
 		--with-system-zlib \
-		--with-theme="breeze sifr" \
 		\
 		--without-doxygen \
 		--without-helppack-integration \