Rename buildflag_headers for consistency

This updates rlz.

Targets go from foo_features to foo_buildflags
And similarly the header now has buildflags in the name.

BUG=814485
TEST=covered by build

Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I802e3e09554fc8564c265d6bb6a9df08ec368081
Reviewed-on: https://chromium-review.googlesource.com/990240
Reviewed-by: Nico Weber <[email protected]>
Commit-Queue: Scott Violet <[email protected]>
Cr-Commit-Position: refs/heads/master@{#547535}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 851794fb..2645da7 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -113,7 +113,7 @@
 #include "net/http/http_server_properties_manager.h"
 #include "ppapi/buildflags/buildflags.h"
 #include "printing/buildflags/buildflags.h"
-#include "rlz/features/features.h"
+#include "rlz/buildflags/buildflags.h"
 
 #if BUILDFLAG(ENABLE_APP_LIST)
 #include "chrome/browser/ui/app_list/app_list_syncable_service.h"