gn2bp: rename _is_append_arg for clarity

I think _is_list_arg is a slightly better name, so it isn't going to be
confused with _append_arg (which will be introduced shortly).

Thought about naming some more, and in general we have 3 types of args:
- flags (arg without value)
- value arg (arg with value)
- list arg (multiple args with multiple values)

Will work on cleaning up the grammar.

Test: none
Change-Id: I40491b33780c7ab38e926efea2b28f1135c40e0c

tools/gn2bp/gen_android_bp

@@ -638,14 +638,14 @@ class BaseActionSanitizer():
   def _has_arg(self, arg):
     return arg in self.target.args
 
-  # Whether an arg has multiple occurences (see argparse action='append')
-  def _is_append_arg(self, arg):
+  # Whether an arg has multiple occurences (e.g. see argparse action='append')
+  def _is_list_arg(self, arg):
     return operator.countOf(arg, self.target.args) > 1
 
   def _has_arg_value(self, arg):
     # TODO: we'll probably need a set of helper functions to deal with append
     # args as well.
-    assert(not self._is_append_arg(arg))
+    assert(not self._is_list_arg(arg))
     i = self.target.args.index(arg)
     return not self.target.args[i + 1].startswith('--')
 
@@ -663,7 +663,7 @@ class BaseActionSanitizer():
     self.target.args[position] = value
 
   def _delete_arg(self, arg):
-    assert(not self._is_append_arg(arg))
+    assert(not self._is_list_arg(arg))
     hasValue = self._has_arg_value(arg)
     i = self.target.index(arg)
     self.target.args.pop(i)