wsl/hsakmt: Disable thunk sub-allocator by default

Signed-off-by: Shi.Leslie <Yuliang.Shi@amd.com>
Reviewed-by: Longlong Yao Longlong.Yao@amd.com

libhsakmt.h

@@ -48,6 +48,7 @@ extern int vendor_packet_process;
 extern int enable_vendor_packet;
 extern bool check_avail_sysram;
 extern size_t max_single_alloc_size;
+extern int enable_thunk_sub_allocator;
 
 #undef HSAKMTAPI
 #define HSAKMTAPI __attribute__((visibility ("default")))