sparse/dissect: fix missing definitions for unnamed members of named types

Now that the Linux kernel is built with -fms-extensions, people use this feature more and more often. However, dissect.c doesn't report the definitions of members promoted from unnamed fields of named types.

This means, for example, that

	$ semind search -m def ns_common.ns_id

fails without this change.

Minimal test-case:

	union U { int i; };

	struct S { union U; } v = { .i = 0 };

Before the patch:

   3:8                    def   s S
   1:7                    def   s U
   1:15                   def   m U.i                              int
   3:23                   def   v v                                struct S
   3:23                   -w-   v v                                struct S
   3:30  v                -w-   m S.i                              int

After the patch:

   3:8                    def   s S
   1:7                    def   s U
   1:15                   def   m U.i                              int
   3:19                   def   m S.i                              int
   3:23                   def   v v                                struct S
   3:23                   -w-   v v                                struct S
   3:30  v                -w-   m S.i                              int

---
 dissect.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

index 796b6e4d..04ec89ca 100644
@@ -193,8 +193,19 @@ static bool deanon(struct symbol *base, struct ident *node, struct symbol *paren
 static void report_memdef(struct symbol *sym, struct symbol *mem)
 {
 	mem->kind = sym && sym->type == SYM_ENUM ? 'e' : 'm';
-	if (sym && mem->ident)
+	if (!sym)
+		return;
+	else if (mem->ident)
 		reporter->r_memdef(sym, mem);
+	else {
+		struct symbol *base = mem->ctype.base_type;
+		if (base->ident == sym->ident) // deanon()'ed
+			return;
+		// base->inspected is T, we can override ->pos
+		DO_LIST(base->symbol_list, __mem,
+			__mem->pos = mem->pos;
+			report_memdef(sym, __mem));
+	}
 }
 
 static void examine_sym_node(struct symbol *node, struct symbol *parent)

2.52.0