Auto merge of #46457 - m4b:no_mangle_static, r=michaelwoerister
Auto merge of #46457 - m4b:no_mangle_static, r=michaelwoerister

Don't set the linkage_name for static variables

For `no_mangle` statics:

1. Linkage_name no longer set
2. The static variable also no longer has a dwarf namespace scope

This matches C++ output, which does not set the linkage_name and is not scoped:

e.g. c++:

```
0x000000b6:   DW_TAG_base_type [8]
                DW_AT_name [DW_FORM_strp]       ( .debug_str[0x00000077] = "long int")
                DW_AT_encoding [DW_FORM_data1]  (DW_ATE_signed)
                DW_AT_byte_size [DW_FORM_data1] (0x08)

0x000000bd:   DW_TAG_variable [9]
                DW_AT_name [DW_FORM_strp]       ( .debug_str[0x00000053] = "TEST")
                DW_AT_type [DW_FORM_ref4]       (cu + 0x0048 => {0x00000048})
                DW_AT_external [DW_FORM_flag_present]   (true)
                DW_AT_decl_file [DW_FORM_data1] ("/home/m4b/tmp/bad_debug/test.cpp")
                DW_AT_decl_line [DW_FORM_data1] (14)
                DW_AT_location [DW_FORM_exprloc]        (<0x9> 03 40 10 20 00 00 00 00 00 )

0x000000d2:   DW_TAG_namespace [2] *
                DW_AT_name [DW_FORM_strp]       ( .debug_str[0x0000009d] = "std")

```

and (now) Rust:

```
0x0000002a:   DW_TAG_variable [2]
                DW_AT_name [DW_FORM_strp]       ( .debug_str[0x00000046] = "TEST")
                DW_AT_type [DW_FORM_ref4]       (cu + 0x0045 => {0x00000045})
                DW_AT_external [DW_FORM_flag_present]   (true)
                DW_AT_decl_file [DW_FORM_data1] ("/tmp/test.rs")
                DW_AT_decl_line [DW_FORM_data1] (8)
                DW_AT_alignment [DW_FORM_udata] (1)
                DW_AT_location [DW_FORM_exprloc]        (<0x9> 03 c0 4d 06 00 00 00 00 00 )

0x00000040:   DW_TAG_namespace [3] *
                DW_AT_name [DW_FORM_strp]       ( .debug_str[0x0000004b] = "test")
```

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