[libFuzzer] Use the compiler to link the relocatable object

Rather than invoking the linker directly, let the compiler driver
handle it. This ensures that we use the correct linker in the case
of cross-compiling.

Differential Revision: https://reviews.llvm.org/D127828

NOKEYCHECK=True
GitOrigin-RevId: 7524fe962e479416fd6318407eff4eed5b96a40b
1 file changed