[Bug target/95129] New: aarch64: make outline-atomics work on non-gnu targets

[nsz at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95129

            Bug ID: 95129
           Summary: aarch64: make outline-atomics work on non-gnu targets
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nsz at gcc dot gnu.org
  Target Milestone: ---

the initializer in libgcc uses __getauxval which is not
available on non-gnu targets so outlining atomics is
ineffective.

change the runtime lse check in libgcc such that non-glibc
targets can implement it too (e.g. calling __getauxval via
a weak reference and no #ifdef __gnu_linux__ check allows
a libc to implement it later, unfortunately a non-linux os
may not have the same hwcap mechanism so a more generic
libc<->libgcc abi would be better).