[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