Builds only with warnings

[mchack-work]

With a modern C compiler we get warnings when building qemu but not originating from our code.

The only way to build is to:

../configure --target-list=riscv32-softmmu --disable-werror

So that warnings are not treated as errors. These warnings are possibly already fixed upstream so maybe update here?

FAILED: libqemuutil.a.p/qobject_block-qdict.c.o 
cc -m64 -mcx16 -Ilibqemuutil.a.p -I. -I.. -Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/sysprof-4 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 -I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /home/mc/tillitis/git/qemu/linux-headers -isystem linux-headers -iquote . -iquote /home/mc/tillitis/git/qemu -iquote /home/mc/tillitis/git/qemu/include -iquote /home/mc/tillitis/git/qemu/disas/libvixl -iquote /home/mc/tillitis/git/qemu/tcg/i386 -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-labels -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -fPIE -MD -MQ libqemuutil.a.p/qobject_block-qdict.c.o -MF libqemuutil.a.p/qobject_block-qdict.c.o.d -o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c
In file included from /home/mc/tillitis/git/qemu/include/qapi/qmp/qdict.h:16,
                 from /home/mc/tillitis/git/qemu/include/block/qdict.h:13,
                 from ../qobject/block-qdict.c:11:
/home/mc/tillitis/git/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’:
/home/mc/tillitis/git/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used uninitialized [-Werror=maybe-uninitialized]
   49 |     typeof(obj) _obj = (obj);                                   \
      |                 ^~~~
../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here
  227 |         QDict *subqdict;
      |                ^~~~~~~~
cc1: all warnings being treated as errors

[quite]

I have documented the required configure line now, with reference to this issue.

[mchack-work]

Use PR to v8.0.0. Closing.