[llvm-exegesis] Add missing MC dependency to CMakeLists.txt
[llvm-exegesis] Add missing MC dependency to CMakeLists.txt

See rL342148

This probably only shows up in BUILD_SHARED_LIBS=ON builds
which might explain how it crept in.

Differential Revision: https://reviews.llvm.org/D52054

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@342180 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm