Skip the PR 14918 linker test for ARM targets.

Skip the PR 14918 linker test for ARM targets.

 I am applying a patch that has been lying around in the Fedora
  binutils sources for a while.  It skips the PR14918 linker test for
  ARM based targets.  This test checks that libgcc is not included in a
  link of an empty executable.  This works for most targets, but on the
  ARM the crt1.o startup code calls __libc_csu_init which is in
  /usr/lib/libc_nonshared.a(elf-init.oS).  This in turn needs
  __aeabi_unwind_cpp_pr0@@GCC_3.5 which is provided by libgcc_s.so.1,
  and so the test fails.