[CFI] Blacklist cronet code

Cronet tests were recently enabled for desktop platforms, some
auto-generated code appears to call function pointers across module
boundaries. Blacklist these calls for now.

Change-Id: If3f7cf2ee84ca86f2d40b80773e5eea1c6e71716
Reviewed-on: https://chromium-review.googlesource.com/1003074Reviewed-by: Peter Collingbourne <pcc@chromium.org>
Commit-Queue: Peter Collingbourne <pcc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549239}

tools/cfi/blacklist.txt

@@ -168,6 +168,7 @@ src:*media/cdm/*
 src:*third_party/swiftshader/*
 src:*base/native_library_unittest.cc
 src:*chrome/browser/ui/libgtkui/app_indicator_icon.cc
+src:*components/cronet/native/*
 
 # chrome/browser/ui/views/frame/global_menu_bar_x11.cc
 fun:*GlobalMenuBarX11*