Orderfile: skip madvise if ordering has not been done.

Change a CHECK to an logged warning if madvise is attempted when code
ordering has not been performed. This happens on upstream builds
including arm64 builds.

Bug: 894748
Change-Id: Icdb7ae0c94cfad5beec0215c6186e29135c1079a
Reviewed-on: https://chromium-review.googlesource.com/c/1278746Reviewed-by: Egor Pasko <pasko@chromium.org>
Reviewed-by: Matthew Cary <mattcary@chromium.org>
Reviewed-by: Benoit L <lizeb@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599201}

base/android/library_loader/library_prefetcher.cc

@@ -320,7 +320,10 @@ void NativeLibraryPrefetcher::PeriodicallyCollectResidency() {
 
 // static
 void NativeLibraryPrefetcher::MadviseForOrderfile() {
-  CHECK(IsOrderingSane());
+  if (!IsOrderingSane()) {
+    LOG(WARNING) << "Code not ordered, madvise optimization skipped";
+    return;
+  }
   LOG(WARNING) << "Performing experimental madvise from orderfile information";
   // First MADV_RANDOM on all of text, then turn the ordered text range back to
   // normal. The ordered range may be placed anywhere within .text.