[lld] [lld][ELF] Enable link script to support absolute path matching (PR #156353)

[Peter Smith via llvm-commits]

smithp35 wrote:

I think a modification of the file pattern to include the path separator would exclude files that have a prefix.
```
#--- script_star.ld
SECTIONS {
  .text : { *(.text) }
  .goo : {
    */bar.o(.text_bar);
    */foo.o(.text_foo);
  }
}
```

As a reviewer I'm reluctant to accept any change to linker scripts that isn't bringing us closer to the documented GNU ld behaviour in https://sourceware.org/binutils/docs/ld/Input-Section.html . Can you check your linker script on GNU ld to see how lld compares to GNU ld? 

If GNU ld and lld behave the same way then sorry I don't think this is the right change to make without getting an equivalent change into GNU ld.

https://github.com/llvm/llvm-project/pull/156353