Simplify around `USE_YJIT` macro (#6240)

* Simplify around `USE_YJIT` macro

- Use `USE_YJIT` macro only instead of `YJIT_BUILD`.
- An intermediate macro `YJIT_SUPPORTED_P` is no longer used.

* Bail out if YJIT is enabled on unsupported platforms

1 files changed, 0 insertions, 1 deletions

diff --git a/vm_core.h b/vm_core.h
index c394862ecb..717f116800 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -495,7 +495,6 @@ struct rb_iseq_constant_body {
 
 #if USE_YJIT
     // YJIT stores some data on each iseq.
-    // Note: Cannot use YJIT_BUILD here since yjit.h includes this header.
     void *yjit_payload;
 #endif
 };