r216566 (r216568 for 4.9 branch) added %{fno-lto} to LINK_COMMAND_SPEC.
However the linker doesn't understand -fno-lto and errors out.
This causes an LTO/PGO bootstrap failure, because -fno-lto is used
during STAGEprofile.
Fixed by filtering out -fno-lto in collect2.c.

From-SVN: r216613