fix comment typo in BUILD.gn

BUG=none
R=andrew@webrtc.org

Review URL: https://codereview.webrtc.org/1370143004 .

Patch from Andrew Bonventre <andybons@chromium.org>.

dl/BUILD.gn

diff --git a/dl/BUILD.gn b/dl/BUILD.gn
index 34d8c5a..2e0e368 100644
--- a/dl/BUILD.gn
+++ b/dl/BUILD.gn
@@ -199,8 +199,8 @@
 
     if (!arm_use_neon) {
       configs -= [ "//build/config/compiler:compiler_arm_fpu" ]
-      // TODO(andybons): Remove cflags once the toolchains have been updated
-      // to use asmflags for assemblers.
+      # TODO(andybons): Remove cflags once the toolchains have been updated
+      # to use asmflags for assemblers.
       cflags = [ "-mfpu=neon" ]
       asmflags = [ "-mfpu=neon" ]
     }