tcg: Optimize inline dup_const for MO_64

Avoid the out-of-line function call for immediate MO_64.
In addition, diagnose all invalid constants at compile-time.

Reviewed-by: David Hildenbrand <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>

Author: rth7680

include/tcg/tcg.h

@@ -1325,7 +1325,8 @@ uint64_t dup_const(unsigned vece, uint64_t c);
      ? (  (VECE) == MO_8  ? 0x0101010101010101ull * (uint8_t)(C)   \
         : (VECE) == MO_16 ? 0x0001000100010001ull * (uint16_t)(C)  \
         : (VECE) == MO_32 ? 0x0000000100000001ull * (uint32_t)(C)  \
-        : dup_const(VECE, C))                                      \
+        : (VECE) == MO_64 ? (uint64_t)(C)                          \
+        : (qemu_build_not_reached_always(), 0))                    \
      : dup_const(VECE, C))