Fix undefined behavior in JIT diagnostic logging

Replace left shift of potentially negative value with multiplication to
avoid undefined behavior detected by UBSan.

In update_branch_imm(), the immediate value (imm) is right-shifted by 2
and can be negative. The diagnostic logging attempted to restore the
original value using left shift (imm << 2), which is undefined behavior
when imm is negative.

Author: jserv

src/jit.c

@@ -594,7 +594,7 @@ static void update_branch_imm(struct jit_state *state,
     assert((imm & 3) == 0);
     uint32_t insn;
     imm >>= 2;
-    rv_log_debug("JIT: Patching branch at offset=%u, imm=%d", offset, imm << 2);
+    rv_log_debug("JIT: Patching branch at offset=%u, imm=%d", offset, imm * 4);
 #if defined(__APPLE__) && defined(__aarch64__)
     /* Must be in write mode to read/write MAP_JIT memory on Apple ARM64 */
     pthread_jit_write_protect_np(false);