Don't skip weak symbols during ar creation

```
$ echo 'int __attribute__((__weak__)) f(void) { return 4; }' > w.c
$ tcc -c w.c -o w.o

$ tcc-old -ar rc w.a w.o; nm -s w.a  # previous behaviour, not indexed
w.o:
0000000000000000 W f

$ ar rc w.a w.o; nm -s w.a           # GNU binutils behaviour, indexed
Archive index:
f in w.o

0000000000000000 W f

$ tcc-new rc w.a w.o; nm -s w.a      # new behaviour, indexed
Archive index:
f in w.o

0000000000000000 W f
```

tcctools.c

@@ -200,6 +200,9 @@ ST_FUNC int tcc_tool_ar(TCCState *s1, int argc, char **argv)
                     (sym->st_info == 0x10
                     || sym->st_info == 0x11
                     || sym->st_info == 0x12
+                    || sym->st_info == 0x20
+                    || sym->st_info == 0x21
+                    || sym->st_info == 0x22
                     )) {
                     //printf("symtab: %2Xh %4Xh %2Xh %s\n", sym->st_info, sym->st_size, sym->st_shndx, strtab + sym->st_name);
                     istrlen = strlen(strtab + sym->st_name)+1;