gdbstub: move breakpoint logic to accel ops

As HW virtualization requires specific support to handle breakpoints
lets push out special casing out of the core gdbstub code and into
AccelOpsClass. This will make it easier to add other accelerator
support and reduces some of the stub shenanigans.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Mads Ynddal <mads@ynddal.dk>
Message-Id: <20220929114231.583801-45-alex.bennee@linaro.org>
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 23b3048..61b27ff 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -617,6 +617,13 @@
     cpus_accel = ops;
 }
 
+const AccelOpsClass *cpus_get_accel(void)
+{
+    /* broken if we call this early */
+    assert(cpus_accel);
+    return cpus_accel;
+}
+
 void qemu_init_vcpu(CPUState *cpu)
 {
     MachineState *ms = MACHINE(qdev_get_machine());