tcg: correctly mark dead inputs for mov with a constant

tcg: correctly mark dead inputs for mov with a constant

When tcg_reg_alloc_mov propagate a constant, we failed to correctly mark
a temp as dead if the liveness analysis hints so. This fixes the
following assert when configure with --enable-debug-tcg:

  qemu-x86_64: tcg/tcg.c:1827: tcg_reg_alloc_bb_end: Assertion `ts->val_type == TEMP_VAL_DEAD' failed.

Cc: Richard Henderson <[email protected]>
Reported-by: Richard Henderson <[email protected]>
Signed-off-by: Aurelien Jarno <[email protected]>
Message-Id: <1437994568[email protected]>
Signed-off-by: Richard Henderson <[email protected]>