accel/tcg: Fix overwrite problems of tcg_cflags

CPUs often set CF_PCREL in tcg_cflags before qemu_init_vcpu(), in which
tcg_cflags will be overwrited by tcg_cpu_init_cflags().

Fixes: 4be79026 ("accel/tcg: Replace `TARGET_TB_PCREL` with `CF_PCREL`")
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
Message-Id: <20230331150609.114401-6-liweiwei@iscas.ac.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

accel/tcg/tcg-accel-ops.c

@@ -59,7 +59,7 @@ void tcg_cpu_init_cflags(CPUState *cpu, bool parallel)
 
     cflags |= parallel ? CF_PARALLEL : 0;
     cflags |= icount_enabled() ? CF_USE_ICOUNT : 0;
-    cpu->tcg_cflags = cflags;
+    cpu->tcg_cflags |= cflags;
 }
 
 void tcg_cpus_destroy(CPUState *cpu)