Revert "Use -Werror in external/bison"

This reverts commit 75d9635354cfbb5368b4ba3cf8c643ff02d378bc.

Change-Id: I4d1d617401b35d698c88c7f25e6b44efb924162c
diff --git a/Android.mk b/Android.mk
index 13be015..59fa45f 100644
--- a/Android.mk
+++ b/Android.mk
@@ -132,8 +132,6 @@
     lib/fcntl.c
 endif
 
-LOCAL_CFLAGS := -Wall -Werror -Wno-sign-compare
-
 include $(BUILD_HOST_STATIC_LIBRARY)
 ###########################################
 
@@ -145,11 +143,7 @@
     $(LOCAL_PATH)/$(BUILD_OS)-lib \
     $(LOCAL_PATH)/lib
 
-LOCAL_CFLAGS := -DPKGDATADIR=\"$(LOCAL_PATH)/data\" \
-    -Wall -Werror \
-    -Wno-sign-compare \
-    -Wno-sometimes-uninitialized \
-    -Wno-unused-parameter \
+LOCAL_CFLAGS := -DPKGDATADIR=\"$(LOCAL_PATH)/data\"
 
 LOCAL_STATIC_LIBRARIES := libbison