libxml2: build host static lib with -fPIC

libxslt/host is complaing that static libxml2 should be with -fPIC.
Unconditionally enable -fPIC for for host build of libxml2.

Fixes: dc701d61b ("libxml2: don't build host shared libraries")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

libs/libxml2/Makefile

@@ -105,6 +105,7 @@ CONFIGURE_ARGS += \
 HOST_CONFIGURE_ARGS += \
 	--disable-shared \
 	--enable-static \
+	--with-pic \
 	--with-c14n \
 	--without-catalog \
 	--with-debug \