Commit 72ff9acad2 caused st_atime,
st_ctime, and st_mtime to be defined as macros. This collided with
use of these identifiers as field names in struct gdb_stat (which
represents the GDB RSP encoding of struct stat) in libgloss
semihosting support for nios2 and m68k. This patch renames the
affected fields of struct gdb_stat.
Signed-off-by: Sandra Loosemore <sandra@codesourcery.com>