Use 0xffffffffffffffffLL to silence GCC 6 warning

Use 0xffffffffffffffffLL to silence GCC 6 warning

GCC 6 warns:

error: result of ‘4294967295ll << 32’ requires 65 bits to represent, but ‘long long int’ only has 64 bits [-Werror=shift-overflow=]

on ((((bfd_signed_vma) 0xffffffff) << 32) | 0xffffffff).  This patch
replaces it with bfd_signed_vma) 0xffffffffffffffffLL.

	* stabs.c (parse_stab_range_type): Use 0xffffffffffffffffLL.