Switch clang to run ld directly on linux. I tested this on all the linux

distros listed by running

gcc main.o -o main
g++ main.o -o main
gcc main.o -o main -static
g++ main.o -o main -static
gcc f.o -o f.so -shared
g++ f.o -o f.so -shared

and comparing the ld line with the one created by clang. I also added
-m32/m64 in distros that support it.

While I tested many distros, there will always be more. If you are hit by this
it should be somewhat easy to add your distro. If you are in a hurry, do
revert this, but please inform how to detect you distro and the ld command
lines produced by the above gcc invocations. Most distros have some patches
on gcc :-(

llvm-svn: 118149