sjlj.S (CONCAT1, [...]): Respond to __USER_LABEL_PREFIX__ for targets that use it.
libitm:
* config/x86/sjlj.S (CONCAT1, CONCAT2, SYM): Respond to
__USER_LABEL_PREFIX__ for targets that use it.
TYPE, SIZE, HIDDEN): New macros to assist on non-elf targets.
(_ITM_beginTransaction): Use SYM, TYPE, SIZE macros to assist
in portability to non-elf targets.
(GTM_longjmp): LIkewise.
* libitm_i.h (begin_transaction): Apply __USER_LABEL_PREFIX__
where required.