automake: intel: correctly append to the LIBADD variable

Commit 05fc62d89f5 sets the variable, yet it forgot the update the
existing reference to append (instead of assign).

Thus as-is the expat library was discarded from the link chain when
building with Android.

Fixes: 05fc62d89f5 ("automake: intel: move expat handling where it's
used")
Cc: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
1 file changed