Reduce ASAN native stack check gap

Summary:
This was causing RangeErrors to be reported too early in ASAN,
and reducing it by half doesn't appear to cause crashes in any tests.

Reviewed By: tmikov

Differential Revision: D67346000

fbshipit-source-id: 0c5529eb427c6c6d2a11d1f9accec86c02ff09b0

include/hermes/VM/Runtime.h

@@ -1695,7 +1695,7 @@ class ScopedNativeDepthReducer {
   // This is empirically good enough.
   static constexpr int kReducedNativeStackGap =
 #if LLVM_ADDRESS_SANITIZER_BUILD
-      256 * 1024;
+      128 * 1024;
 #else
       32 * 1024;
 #endif

lib/VM/Runtime.cpp

@@ -86,7 +86,7 @@ static constexpr uint32_t kMaxSupportedNumRegisters =
 /// The minimum stack gap allowed from RuntimeConfig.
 static constexpr uint32_t kMinSupportedNativeStackGap =
 #if LLVM_ADDRESS_SANITIZER_BUILD
-    512 * 1024;
+    256 * 1024;
 #else
     64 * 1024;
 #endif