[sanitizer] decrease sanitizer-coverage-block-threshold from 1000 to 500 as another horrible workaround for PR17409

llvm-svn: 231733
diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index 6000fd0..fcb6ab0 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -72,7 +72,7 @@
     "sanitizer-coverage-block-threshold",
     cl::desc("Use a callback with a guard check inside it if there are"
              " more than this number of blocks."),
-    cl::Hidden, cl::init(1000));
+    cl::Hidden, cl::init(500));
 
 static cl::opt<bool>
     ClExperimentalTracing("sanitizer-coverage-experimental-tracing",