include: Make headers more self-contained

Back in 2016, we discussed[1] rules for headers, and these were
generally liked:

1. Have a carefully curated header that's included everywhere first.  We
   got that already thanks to Peter: osdep.h.

2. Headers should normally include everything they need beyond osdep.h.
   If exceptions are needed for some reason, they must be documented in
   the header.  If all that's needed from a header is typedefs, put
   those into qemu/typedefs.h instead of including the header.

3. Cyclic inclusion is forbidden.

This patch gets include/ closer to obeying 2.

It's actually extracted from my "[RFC] Baby steps towards saner
headers" series[2], which demonstrates a possible path towards
checking 2 automatically.  It passes the RFC test there.

[1] Message-ID: <87h9g8j57d.fsf@blackfin.pond.sub.org>
    https://lists.nongnu.org/archive/html/qemu-devel/2016-03/msg03345.html
[2] Message-Id: <20190711122827.18970-1-armbru@redhat.com>
    https://lists.nongnu.org/archive/html/qemu-devel/2019-07/msg02715.html

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190812052359.30071-2-armbru@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>

include/hw/ppc/pnv_core.h

@@ -21,6 +21,7 @@
 #define PPC_PNV_CORE_H
 
 #include "hw/cpu/core.h"
+#include "target/ppc/cpu.h"
 
 #define TYPE_PNV_CORE "powernv-cpu-core"
 #define PNV_CORE(obj) \

include/hw/ppc/ppc4xx.h

@@ -25,6 +25,10 @@
 #ifndef PPC4XX_H
 #define PPC4XX_H
 
+#include "hw/ppc/ppc.h"
+#include "exec/cpu-common.h"
+#include "exec/memory.h"
+
 /* PowerPC 4xx core initialization */
 PowerPCCPU *ppc4xx_init(const char *cpu_model,
                         clk_setup_t *cpu_clk, clk_setup_t *tb_clk,

include/hw/ppc/spapr_irq.h

@@ -10,6 +10,9 @@
 #ifndef HW_SPAPR_IRQ_H
 #define HW_SPAPR_IRQ_H
 
+#include "hw/irq.h"
+#include "target/ppc/cpu-qom.h"
+
 /*
  * IRQ range offsets per device type
  */

include/hw/ppc/spapr_vio.h

@@ -22,6 +22,7 @@
  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "hw/ppc/spapr.h"
 #include "sysemu/dma.h"
 
 #define TYPE_VIO_SPAPR_DEVICE "vio-spapr-device"

include/hw/ppc/spapr_xive.h

@@ -10,7 +10,9 @@
 #ifndef PPC_SPAPR_XIVE_H
 #define PPC_SPAPR_XIVE_H
 
+#include "hw/ppc/spapr_irq.h"
 #include "hw/ppc/xive.h"
+#include "sysemu/sysemu.h"
 
 #define TYPE_SPAPR_XIVE "spapr-xive"
 #define SPAPR_XIVE(obj) OBJECT_CHECK(SpaprXive, (obj), TYPE_SPAPR_XIVE)

include/hw/ppc/xive_regs.h

@@ -16,6 +16,9 @@
 #ifndef PPC_XIVE_REGS_H
 #define PPC_XIVE_REGS_H
 
+#include "qemu/bswap.h"
+#include "qemu/host-utils.h"
+
 /*
  * Interrupt source number encoding on PowerBUS
  */