libxslt, fix build for gcc2 (#5518)

dev-libs/libxslt/libxslt-1.1.34.recipe

@@ -8,7 +8,7 @@ in commercial applications."
 HOMEPAGE="http://www.xmlsoft.org/"
 COPYRIGHT="2001-2012 Daniel Veillard"
 LICENSE="MIT"
-REVISION="2"
+REVISION="3"
 SOURCE_URI="ftp://xmlsoft.org/libxml2/libxslt-$portVersion.tar.gz"
 CHECKSUM_SHA256="98b1bd46d6792925ad2dfe9a87452ea2adebf69dcb9919ffd55bf926a7f93f7f"
 
@@ -59,7 +59,7 @@ PATCH()
 {
 	if [ "$effectiveTargetArchitecture" = x86_gcc2 ]; then
 		sed -i \
-			-e "s/ -Wmissing-format-attribute//" \
+			-E "s/( -Wextra| -Wmissing-format-attribute)//g" \
 			configure.ac
 	fi
 }