Use g_new() & friends where that makes obvious sense

g_new(T, n) is neater than g_malloc(sizeof(T) * n).  It's also safer,
for two reasons.  One, it catches multiplication overflowing size_t.
Two, it returns T * rather than void *, which lets the compiler catch
more type errors.

This commit only touches allocations with size arguments of the form
sizeof(T).

Patch created mechanically with:

    $ spatch --in-place --sp-file scripts/coccinelle/use-g_new-etc.cocci \
	     --macro-file scripts/cocci-macro-file.h FILES...

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20220315144156.1595462-4-armbru@redhat.com>
Reviewed-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>

dump/dump.c

@@ -2041,7 +2041,7 @@ void qmp_dump_guest_memory(bool paging, const char *file,
 DumpGuestMemoryCapability *qmp_query_dump_guest_memory_capability(Error **errp)
 {
     DumpGuestMemoryCapability *cap =
-                                  g_malloc0(sizeof(DumpGuestMemoryCapability));
+                                  g_new0(DumpGuestMemoryCapability, 1);
     DumpGuestMemoryFormatList **tail = &cap->formats;
 
     /* elf is always available */