softmmu/watchpoint: Add missing 'qemu/error-report.h' include

softmmu/watchpoint: Add missing 'qemu/error-report.h' include

cpu_watchpoint_insert() calls error_report() which is declared
in "qemu/error-report.h". When moving this code in commit 2609ec2868
("softmmu: Extract watchpoint API from physmem.c") we neglected to
include this header. This works so far because it is indirectly
included by TCG headers -> "qemu/plugin.h" -> "qemu/error-report.h".

Currently cpu_watchpoint_insert() is only built with the TCG
accelerator. When building it with other ones (or without TCG)
we get:

  softmmu/watchpoint.c:38:9: error: implicit declaration of function 'error_report' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        error_report("tried to set invalid watchpoint at %"
        ^

Include "qemu/error-report.h" in order to fix this for non-TCG
builds.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230328173117.15226-3-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>