No, I think -Wl,--gc-sections still produces unwind data for the functions that remain. I suppose you could use the strip command on relocatable (intermediate) .o files. But the most common approach is probably building with -fno-exceptions -fno-unwind-tables -fno-asynchronous-unwind-tables. Or perhaps the toolchain defaults to that when building C, which is an odd configuration for GNU/Linux because pthread_cancel actually uses unwinding in C (and -fexceptions avoids an unprotected function pointer on the stack that is called even on the non-canceling code path).
