dump: Drop qmp_dump_guest_memory() stub and build for all targets

qmp_dump_guest_memory() calls dump_init() and returns an Error when
cpu_get_dump_info() returns an error, as done by the stub.
So there is no need to have a stub for qmp_dump_guest_memory().

Enable the documentation of the always-present dump-guest-memory command.

That way we can drop CONFIG_HAVE_CORE_DUMP and leave configure
completely out of the picture for target CPU features.
Signed-off-by: NAndreas Färber <afaerber@suse.de>

Makefile.target

@@ -110,7 +110,7 @@ obj-$(CONFIG_FDT) += device_tree.o
 obj-$(CONFIG_KVM) += kvm-all.o
 obj-y += memory.o savevm.o cputlb.o
 obj-y += memory_mapping.o
-obj-$(CONFIG_HAVE_CORE_DUMP) += dump.o
+obj-y += dump.o
 LIBS+=$(libs_softmmu)
 
 # xen support

configure

@@ -4303,10 +4303,6 @@ if test "$target_bigendian" = "yes" ; then
 fi
 if test "$target_softmmu" = "yes" ; then
   echo "CONFIG_SOFTMMU=y" >> $config_target_mak
-  case "$target_arch2" in
-    i386|x86_64)
-      echo "CONFIG_HAVE_CORE_DUMP=y" >> $config_target_mak
-  esac
 fi
 if test "$target_user_only" = "yes" ; then
   echo "CONFIG_USER_ONLY=y" >> $config_target_mak

hmp-commands.hx

@@ -991,7 +991,6 @@ server will ask the spice/vnc client to automatically reconnect using the
 new parameters (if specified) once the vm migration finished successfully.
 ETEXI
 
-#if defined(CONFIG_HAVE_CORE_DUMP)
     {
         .name       = "dump-guest-memory",
         .args_type  = "paging:-p,filename:F,begin:i?,length:i?",
@@ -1015,7 +1014,6 @@ gdb.
     length: the memory size, in bytes. It's optional, and should be specified
             with begin together.
 ETEXI
-#endif
 
     {
         .name       = "snapshot_blkdev",

stubs/dump.c

@@ -16,14 +16,6 @@
 #include "qapi/qmp/qerror.h"
 #include "qmp-commands.h"
 
-/* we need this function in hmp.c */
-void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
-                           int64_t begin, bool has_length, int64_t length,
-                           Error **errp)
-{
-    error_set(errp, QERR_UNSUPPORTED);
-}
-
 int cpu_get_dump_info(ArchDumpInfo *info)
 {
     return -1;