message: Modify CMakeLists to split up vcpkglib
  Before this, we had vcpkg and vcpkg-test taking the vcpkglib source
  files directory -- this commit makes vcpkglib an object library.
diff: @@ -43,14 +43,22 @@ else()
  set(DISABLE_METRICS_VALUE "0")
  endif()
  -add_executable(vcpkg src/vcpkg.cpp ${VCPKGLIB_SOURCES})
  -target_compile_definitions(vcpkg PRIVATE -DDISABLE_METRICS=${DISABLE_METRICS_VALUE})
  -target_include_directories(vcpkg PRIVATE include)
  -
  +add_library(vcpkglib OBJECT ${VCPKGLIB_SOURCES})
  +add_executable(vcpkg src/vcpkg.cpp $<TARGET_OBJECTS:vcpkglib>)
  +add_executable(vcpkg-test
  + EXCLUDE_FROM_ALL
  + ${VCPKGTEST_SOURCES}
  + $<TARGET_OBJECTS:vcpkglib>)
  +
  +foreach(TARGET_NAME vcpkglib vcpkg vcpkg-test)
  + target_compile_definitions(${TARGET_NAME} PRIVATE -DDISABLE_METRICS=${DISABLE_METRICS_VALUE})
  + target_include_directories(${TARGET_NAME} PRIVATE include)
  +endforeach()
  -add_executable(vcpkg-test EXCLUDE_FROM_ALL ${VCPKGTEST_SOURCES} ${VCPKGLIB_SOURCES})
  -target_compile_definitions(vcpkg-test PRIVATE -DDISABLE_METRICS=${DISABLE_METRICS_VALUE})
  -target_include_directories(vcpkg-test PRIVATE include)
  +set(THREADS_PREFER_PTHREAD_FLAG ON)
  +find_package(Threads REQUIRED)
  +target_link_libraries(vcpkg PRIVATE Threads::Threads)
  +target_link_libraries(vcpkg-test PRIVATE Threads::Threads)
  foreach(TEST_NAME
  arguments chrono dependencies files
  @@ -91,8 +99,3 @@ if(MSVC)
  target_sources(vcpkg PRIVATE src/pch.cpp)
  target_compile_options(vcpkg PRIVATE /Yupch.h /FIpch.h /Zm200)
  endif()
  -
  -set(THREADS_PREFER_PTHREAD_FLAG ON)
  -find_package(Threads REQUIRED)
  -target_link_libraries(vcpkg PRIVATE Threads::Threads)
  -target_link_libraries(vcpkg-test PRIVATE Threads::Threads)
  