Extend handling of immediates on ARM's SystemTap SDT probe support

Extend handling of immediates on ARM's SystemTap SDT probe support

Continuing my series of fixes on the SystemTap SDT support for the
ARM/AArch64 architectures, this patch now extends how ARM's SDT specific
parser handles literal numbers (immediates).

Currently, it only accepts "#" as the prefix.  However, according to
"info '(as) ARM-Chars'", expressions can also have "$" and nothing as a
prefix.  This patch extends the parser to accept those options.

2013-12-28  Sergio Durigan Junior  <sergiodj@redhat.com>

	* arm-linux-tdep.c (arm_stap_is_single_operand): Accept "$" as a
	literal prefix.  Also accept no prefix at all.
	(arm_stap_parse_special_token): Likewise.
	(arm_linux_init_abi): Likewise.