D35352: [ELF] - Implement filter library support (-F / --filter)

[George Rimar via llvm-commits]

> I believe `-F` / `--filter` can be used multiple times, as with `-f`.

I think that is true for -f/--auxilary only.

LD manual says that: "This option may be specified more than once. The DT_AUXILIARY entries will be created in the order in which they appear on the command line." 
https://www.freebsd.org/cgi/man.cgi?ld(1)

But it does not say anything about multiple use of '-F/--filter'. 

And both gold/bfd use only last library passed via -F:
ld.bfd -F aa -shared -F dd x.o
readelf -a a.out

Dynamic section at offset 0x190 contains 7 entries:
  Tag        Type                         Name/Value
 0x000000007fffffff (FILTER)             Filter library: [dd]
 0x0000000000000004 (HASH)               0xe8
 0x0000000000000005 (STRTAB)             0x170
 0x0000000000000006 (SYMTAB)             0x110
 0x000000000000000a (STRSZ)              28 (bytes)
 0x000000000000000b (SYMENT)             24 (bytes)
 0x0000000000000000 (NULL)               0x0

George.