Allow specifying a custom supplicant config file

Bug: 364352776, 350971011
Test: m
Change-Id: I0d20ea8c5003c7534c09cc661af7e7211196a568
diff --git a/wpa_supplicant/Android.mk b/wpa_supplicant/Android.mk
index f36b074..1cfa075 100644
--- a/wpa_supplicant/Android.mk
+++ b/wpa_supplicant/Android.mk
@@ -18,7 +18,11 @@
   CONFIG_DRIVER_NL80211_QCA=y
 endif
 
-include $(LOCAL_PATH)/android.config
+ifneq ($(SUPPLICANT_CUSTOM_DEF_CONFIG_FILE_PATH),)
+  include $(SUPPLICANT_CUSTOM_DEF_CONFIG_FILE_PATH)
+else
+  include $(LOCAL_PATH)/android.config
+endif
 
 # To ignore possible wrong network configurations
 L_CFLAGS = -DWPA_IGNORE_CONFIG_ERRORS