gcc: create dummy crtstuff on loongarch64

  #

  SHLIB_LC = lib.optionalString stdenv.targetPlatform.isPower "-mnewlib";

in ''

in

''

  echo 'libgcc.a: ${crtstuff-ofiles}' >> libgcc/Makefile.in

  echo 'SHLIB_LC=${SHLIB_LC}' >> libgcc/Makefile.in

''

  # Meanwhile, crt{i,n}.S are not present on certain platforms

  # (e.g. LoongArch64), resulting in the following error:

  #

  # No rule to make target '../../../gcc-xx.x.x/libgcc/config/loongarch/crti.S', needed by 'crti.o'.  Stop.

  #

  # For LoongArch64, a hacky workaround is to simply touch them,

  # as the platform forces .init_array support.

  #

  # https://www.openwall.com/lists/musl/2022/11/09/3

  #

  + lib.optionalString stdenv.targetPlatform.isLoongArch64 ''

  touch libgcc/config/loongarch/crt{i,n}.S

''