[ELF] - Add separate form for -R alias.

[ELF] - Add separate form for -R alias.

During link of devel/chrpath (FreeBSD port), found next issue:
/usr/bin/ld: error: unclosed comment in a linker script
/usr/bin/ld: error: line 1: unknown directive: �
/usr/bin/ld: error: �\16�

Problem was not obvious and the reason was that we did not accept
the separate form of -R. While invocation line contained it:
cc -Wl,-R /usr/local/lib -o prog prog.c

CPIO file produced contained /usr/local/lib file.
Which looks because of reasons above
contained inside the content of whole lib folder,
and it then was passed as an input and
proccessed as linker script.

llvm-svn: 286378