8310949: RISC-V: Initialize UseUnalignedAccesses

Reviewed-by: rehn, vkempik, fyang

src/hotspot/cpu/riscv/vm_version_riscv.cpp

@@ -204,6 +204,13 @@ void VM_Version::initialize() {
     }
   }
 
+  // See JDK-8026049
+  // This machine has fast unaligned memory accesses
+  if (FLAG_IS_DEFAULT(UseUnalignedAccesses)) {
+    FLAG_SET_DEFAULT(UseUnalignedAccesses,
+      unaligned_access.value() == MISALIGNED_FAST);
+  }
+
   if (UseZbb) {
     if (FLAG_IS_DEFAULT(UsePopCountInstruction)) {
       FLAG_SET_DEFAULT(UsePopCountInstruction, true);