libgcc, emutls: Allow building weak definitions of the emutls functions.
In order to better support use of the emulated TLS between objects with
DSO dependencies and static-linked libgcc, allow a target to make weak
definitions.
Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
libgcc/ChangeLog:
* config/t-darwin: Build weak-defined emutls objects.
* emutls.c (__emutls_get_address): Add optional attributes.
(__emutls_register_common): Likewise.
(EMUTLS_ATTR): New.
(cherry picked from commit
b9873b4e2c9a9955789318f4d550147ef9405b07)