Update buildroot to pull in ubsan updates. (#12821)

DEPS

@@ -136,7 +136,7 @@ allowed_hosts = [
 ]
 
 deps = {
-  'src': 'https://github.com/flutter/buildroot.git' + '@' + 'eb6a23609da39c7e20c47ee6d041466ce9a7b63c',
+  'src': 'https://github.com/flutter/buildroot.git' + '@' + 'edd0f2d19604a7d63deb20e9c19c1412acb8a9bd',
 
    # Fuchsia compatibility
    #

tools/gn

@@ -269,6 +269,9 @@ def to_gn_args(args):
     if args.lsan:
       gn_args['is_lsan'] = True
 
+    if args.ubsan:
+      gn_args['is_ubsan'] = True
+
     return gn_args
 
 def parse_args(args):
@@ -347,6 +350,7 @@ def parse_args(args):
   parser.add_argument('--lsan', default=False, action='store_true')
   parser.add_argument('--msan', default=False, action='store_true')
   parser.add_argument('--tsan', default=False, action='store_true')
+  parser.add_argument('--ubsan', default=False, action='store_true')
 
   return parser.parse_args(args)