gas: move code for object attribute parsing into obj-elf-attr.c

Gas, contrarilly to others binutils tools, is compiled for a specific
target. Some targets don't support Object Attributes (OAs). For those
cases, today the OA directive ".gnu_attribute" is still enabled but the
processing would probably fail in most of cases because the named tag
would be unknown. Most of the parsing code on such a target can be
considered as dead code.

This patch aims at removing this dead code from Gas when the target does
not support the OAs by:
- moving the code of OA parsing into a separate file under gas/config
  which is only included for the relevant targets supporting OAs.
- disabling the code related to OAs on non-OA target via a TC_OBJ_ATTR
  macro.

Adding/removing the OA feature from Gas for a specific target can easilly
be done from tc-<arch>.h by changing the values of TC_OBJ_ATTR: 1 enabled,
0 disabled. You might also want to guard the enablement of OAs only for
ELF targets with OBJ_ELF (see example below).

\#ifdef OBJ_ELF
/* The target supports Object Attributes.  */
\#define TC_OBJ_ATTR 1
\#endif

0 files changed, 0 insertions, 0 deletions