Reland https://skia-review.googlesource.com/c/6091/

The only difference is that we now also put the guard flag
SK_SUPPORT_LEGACY_AAA in SkUserConfig.h. Previously, SkAnalyticEdge.cpp doesn't
get that flag from SkScan.h and that caused many problems.

BUG=skia:
TBR=reed@google.com,caryclark@google.com

Change-Id: I134bb76cebd6fffa712f438076668765321bba3b
Reviewed-on: https://skia-review.googlesource.com/6992
Reviewed-by: Yuqian Li <liyuqian@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index 34aaee8..7e05319 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -1198,6 +1198,10 @@
 
     gSkUseAnalyticAA = FLAGS_analyticAA;
 
+    if (FLAGS_forceAnalyticAA) {
+        gSkForceAnalyticAA = true;
+    }
+
     int runs = 0;
     BenchmarkStream benchStream;
     while (Benchmark* b = benchStream.next()) {