Allow EROFS to be incompatible with the platform

Just because the tools are built, doesn't mean erofs will actually be
used. Don't hold the user's build hostage.

Change-Id: I56086cabda7f84805a0f6b3e456b98191ab731b2
diff --git a/Android.bp b/Android.bp
index 02c8f08..7c5e89d 100644
--- a/Android.bp
+++ b/Android.bp
@@ -57,6 +57,7 @@
     cflags: [
         "-Wall",
         "-Werror",
+        "-Wno-error=#warnings",
         "-Wno-ignored-qualifiers",
         "-Wno-pointer-arith",
         "-Wno-unused-parameter",