#3370 crash on array declaration with extra braces after function definition

[Philipp Klaus Krause]

The following code makes current SDCC crash:

void f (void)
{
}

const int i[]={{1,2},{3,4}};

Depending on the port, I see either a segfault, or an

Internal error: validateLink failed in SPEC_NOUN(type) @ SDCCsymt.c:3819: expected SPECIFIER, got UNKNOWN

[Christopher Bazley]

Original brace example produces warning 147 without crashing on MCS51, Z80 and STM8.
https://godbolt.org/z/38sWK5j7n

[Christopher Bazley]

Added regression test in [r17057]