Include elfos.h before ${tm_file}.

Include elfos.h before ${tm_file}.

Fixes:

In file included from ./tm.h:23,
                  from gcc/genconfig.c:25:
gcc/config/elfos.h:209: warning: "READONLY_DATA_SECTION_ASM_OP" redefined
   209 | #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
       |
In file included from ./tm.h:21,
                  from gcc/genconfig.c:25:
gcc/config/epiphany/epiphany.h:671: note: this is the location of the previous definition
   671 | #define READONLY_DATA_SECTION_ASM_OP    "\t.section .rodata"

gcc/ChangeLog:

	* config.gcc: Include elfos.h before ${tm_file}.