Use -Werror in external/wpa_supplicant_8

* Suppress existing warnings.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I292638ff939dafcc2d88936f31eb7ce2e9659576
diff --git a/wpa_supplicant/Android.mk b/wpa_supplicant/Android.mk
index 867af85..5ae09dd 100644
--- a/wpa_supplicant/Android.mk
+++ b/wpa_supplicant/Android.mk
@@ -22,6 +22,14 @@
 # Set Android log name
 L_CFLAGS += -DANDROID_LOG_NAME=\"wpa_supplicant\"
 
+L_CFLAGS += -Wall -Werror
+
+# Disable unused function warnings
+L_CFLAGS += -Wno-unused-function
+
+# Disable unused variable warnings
+L_CFLAGS += -Wno-unused-variable
+
 # Disable unused parameter warnings
 L_CFLAGS += -Wno-unused-parameter