Support non-Win32 multiconfig generators

clang: error: no such file or directory: '/Users/bbannier/src/mesos/_xcode/3rdparty/protobuf-3.3.0/src/protobuf-3.3.0-build/libprotobuf.dylib'
clang: error: no such file or directory: '/Users/bbannier/src/mesos/_xcode/3rdparty/googletest-1.8.0/src/googletest-1.8.0-build/googlemock/libgmock.a'
clang: error: no such file or directory: '/Users/bbannier/src/mesos/_xcode/3rdparty/googletest-1.8.0/src/googletest-1.8.0-build/googlemock/gtest/libgtest.a'

if (WIN32)
  set_target_properties(
    protobuf PROPERTIES
    IMPORTED_LOCATION_DEBUG ${PROTOBUF_ROOT}-build/Debug/libprotobufd${LIBRARY_SUFFIX}
    IMPORTED_LOCATION_RELEASE ${PROTOBUF_ROOT}-build/Release/libprotobuf${LIBRARY_SUFFIX})

  set_target_properties(
    protoc PROPERTIES
    IMPORTED_LOCATION_DEBUG ${PROTOBUF_ROOT}-build/Debug/protoc.exe
    IMPORTED_LOCATION_RELEASE ${PROTOBUF_ROOT}-build/Release/protoc.exe)
else ()
  # This is for single-configuration generators such as GNU Make.
  if (CMAKE_BUILD_TYPE MATCHES DEBUG)
    set(PROTOBUF_SUFFIX d)
  endif ()

  set_target_properties(
    protobuf PROPERTIES
    IMPORTED_LOCATION ${PROTOBUF_ROOT}-build/libprotobuf${PROTOBUF_SUFFIX}${LIBRARY_SUFFIX})

  set_target_properties(
    protoc PROPERTIES
    IMPORTED_LOCATION ${PROTOBUF_ROOT}-build/protoc)
endif ()