meson: Remove --warn-common ldflag

meson: Remove --warn-common ldflag

--warn-common ldflag causes warnings for multiple definitions of
___asan_globals_registered when enabling AddressSanitizer with clang.
The warning is somewhat obsolete so just remove it.

The common block is used to allow duplicate definitions of uninitialized
global variables. In the past, GCC and clang used to place such
variables in a common block by default, which prevented programmers for
noticing accidental duplicate definitions. Commit 49237acdb725 ("Enable
ld flag --warn-common") added --warn-common ldflag so that ld warns in
such a case.

Today, both of GCC and clang don't use common blocks by default[1][2] so
any remaining use of common blocks should be intentional. Remove
--warn-common ldflag to suppress warnings for intentional use of
common blocks.

[1]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85678
[2]: https://reviews.llvm.org/D75056

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20240304-common-v1-1-1a2005d1f350@daynix.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>