When addr2line output contains discriminator, the current awk script
cannot parse it.  This patch fixes it by extracting key words using
regex which is more reliable.

  $ scripts/faddr2line vmlinux tlb_flush_mmu_free+0x26
  tlb_flush_mmu_free+0x26/0x50:
  tlb_flush_mmu_free at mm/memory.c:258 (discriminator 3)
  scripts/faddr2line: eval: line 173: unexpected EOF while looking for matching `)'

Link: http://lkml.kernel.org/r/1525323379-25193-1-git-send-email-changbin.du@intel.com
Fixes: 6870c016 ("scripts/faddr2line: show the code context")
Signed-off-by: Changbin Du <changbin.du@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: NeilBrown <neilb@suse.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>