Avoid using 'template' C++ keyword

Avoid using 'template' C++ keyword

'template' is used in include/opcode/aarch64.h as below,

 typedef struct
 {
   const char *template;
   uint32_t value;
   int has_xt;
 } aarch64_sys_ins_reg;

and it triggers compilation errors when GDB is built in C++ mode.

In file included from git/gdb/aarch64-tdep.c:62:0:
git/gdb/../include/opcode/aarch64.h:651:15: error: expected unqualified-id before 'template'
   const char *template;

This patch is to rename field template to name.

gas/

	* config/tc-aarch64.c (md_begin): Access field 'name' rather
	than 'template'.

include/opcode/

	* aarch64.h (aarch64_sys_ins_reg) <template>: Removed.
	<name>: New field.

opcodes/

	* aarch64-dis.c (aarch64_ext_sysins_op): Access field
	'name' rather than 'template'.
	* aarch64-opc.c (aarch64_print_operand): Likewise.