[Bug target/126723] aarch64-darwin: temporary L.str labels miscompile literals after a weak_definition

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126723

--- Comment #4 from Iain Sandoe <iains at gcc dot gnu.org> ---
As background, the reason that I made the non-ASAN symbols L is that clang does
not always make string labels 'l' (see below) - in general, it is inefficient
to make more symbols than necessary linker-visible (more relocations, bigger .o
files and more linker load) .. however, the current TARGET_MACRO scheme does
not make it feasible to have a complex algorithm - I have a WIP branch to try
and improve this - but probably a short-term fix is to fall back to all strings
being linker-vis (definitely for the upcoming 16.2 release)

=== clang 17:


e.g:

        .section        __TEXT,__cstring,cstring_literals
L_.str:                                 ## @.str
        .asciz  "try...."

L_.str.1:                               ## @.str.1
        .asciz  "Hello, C++ world. from "

L_.str.2:                               ## @.str.2
        .asciz  "Apple LLVM 17.0.0 (clang-1700.6.3.2)"