linux-user/riscv: initialise the TaskState heap/stack info

Arguably the target_cpu_copy_regs function for each architecture is
misnamed as a number of the architectures also take the opportunity to
fill out the TaskState structure. This could arguably be factored out
into common code but that would require a wider audit of the
architectures. For now just replicate for riscv so we can correctly
report semihosting information for SYS_HEAPINFO.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20210323165308.15244-9-alex.bennee@linaro.org>

linux-user/riscv/cpu_loop.c

@@ -135,4 +135,9 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
         error_report("Incompatible ELF: RVE cpu requires RVE ABI binary");
         exit(EXIT_FAILURE);
     }
+
+    ts->stack_base = info->start_stack;
+    ts->heap_base = info->brk;
+    /* This will be filled in on the first SYS_HEAPINFO call.  */
+    ts->heap_limit = 0;
 }