erlang: Enable compiler warnings for the library

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@990959 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/erl/build/otp.mk b/lib/erl/build/otp.mk
index 1d16e2c..0e0381e 100644
--- a/lib/erl/build/otp.mk
+++ b/lib/erl/build/otp.mk
@@ -25,7 +25,6 @@
 
 # MHOST is the host where this Makefile runs.
 MHOST=${shell hostname -s}
-ERL_COMPILE_FLAGS+=-W0
 
 # The location of the erlang runtime system.
 ifndef ERL_RUN_TOP