unix/variants: Prefer unix-ffi packages when loading the manifest.

Signed-off-by: Damien George <damien@micropython.org>

ports/unix/variants/coverage/manifest.py

@@ -1,3 +1,4 @@
+add_library("unix-ffi", "$(MPY_LIB_DIR)/unix-ffi")
 freeze_as_str("frzstr")
 freeze_as_mpy("frzmpy")
 freeze_mpy("$(MPY_DIR)/tests/frozen")

ports/unix/variants/manifest.py

@@ -1,2 +1,3 @@
+add_library("unix-ffi", "$(MPY_LIB_DIR)/unix-ffi")
 require("mip-cmdline")
 require("ssl")