Relax sysprop neverallow rules for Fuchsia targets.

Bug: 142796797
Test: Fuchsia targets build.

Change-Id: I39ec3689d5b11209f8a12b3686974eb312c3b370
diff --git a/BoardConfig_common.mk b/BoardConfig_common.mk
index 4285b4e..983f200 100644
--- a/BoardConfig_common.mk
+++ b/BoardConfig_common.mk
@@ -18,3 +18,4 @@
 TARGET_NO_KERNEL := true
 TARGET_NO_RECOVERY := true
 DISABLE_APEX_LIBS_ABSENCE_CHECK := true
+BUILD_BROKEN_TREBLE_SYSPROP_NEVERALLOW := true