enable -Werror by default

People keep adding code with warnings, so enable -Werror to prevent that.

BUG=None
TEST=`FEATURES=test emerge-x86-alex platform2` passes
TEST=`FEATURES=test emerge-daisy platform2` passes
TEST=`FEATURES=test emerge-lumpy platform2` passes

Change-Id: Iea0e739b6249eaf70c5263504e08bbdc532f3afe
Reviewed-on: https://chromium-review.googlesource.com/180921
Reviewed-by: Daniel Erat <derat@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/common.gypi b/common.gypi
index fe00d13..15ddb61 100644
--- a/common.gypi
+++ b/common.gypi
@@ -3,8 +3,8 @@
 
 {
   'variables': {
-    # Set this to 1 if you'd like to enable -Werror.
-    'enable_werror%': 0,
+    # Set this to 0 if you'd like to disable -Werror.
+    'enable_werror%': 1,
 
     # Set this to 1 if you'd like to enable debugging flags.
     'debug%': 0,