Mark __jit_debug_register_code as a unique symbol

This symbol is used to notify the debugger about JIT library load/unload
events. Because of ICF, several functions with the same body put to the
same adress by the linker what causes the debugger to get notifictaion
about JIT load/unload events in several case where it isn't really happened.

This change disable ICF for the __jit_debug_register_code symbol to prevent
this behavior with keeping the symbol unique in the object file.

This is the recommit of 5caf652d after
fixing the compilation issue on sdk_phone_armv7-sdk (mac) target.

Change-Id: I027d2c7964098d47ed350ee6b7c74d82c88a5d1f