Arm/COFF: accept .def outside of CCS mode

There's no reason to reject this common COFF directive when it doesn't
have any other meaning.

binutils/testsuite/binutils-all/nm.exp

@@ -163,7 +163,7 @@ if {   [is_elf_format]
     || [istarget wasm32-*-*]
     || [istarget bpf-*-*]} {
     set nm_1_src "nm-elf-1.s"
-} elseif {[is_coff_format] && ![istarget arm*-*-*]} {
+} elseif {[is_coff_format]} {
     if {[istarget *c4x-*-*] || [istarget *c54x-*-*]} {
 	set nm_1_src "nm-coff-sdef-1.s"
     } else {

gas/config/obj-coff.c

@@ -569,7 +569,7 @@ obj_coff_ident (int ignore ATTRIBUTE_UNUSED)
 #define SKIP_WHITESPACES()	while (is_whitespace (*input_line_pointer)) \
                                   input_line_pointer++;
 
-static void
+void
 obj_coff_def (int what ATTRIBUTE_UNUSED)
 {
   if (def_symbol_in_progress != NULL)

gas/config/obj-coff.h

@@ -330,7 +330,7 @@ extern void pecoff_obj_clear_weak_hook   (symbolS *);
 #endif
 extern void obj_coff_section             (int);
 extern segT obj_coff_add_segment         (const char *);
-extern void obj_coff_section             (int);
+extern void obj_coff_def                 (int);
 extern segT s_get_segment                (symbolS *);
 #ifndef tc_coff_symbol_emit_hook
 extern void tc_coff_symbol_emit_hook     (symbolS *);

gas/config/tc-arm.c

@@ -3434,7 +3434,11 @@ s_ccs_def (int name)
   if (codecomposer_syntax)
     s_globl (name);
   else
+#ifdef OBJ_COFF
+    obj_coff_def (name);
+#else
     as_bad (_(".def pseudo-op only available with -mccs flag."));
+#endif
 }
 
 /* Directives: Literal pools.  */