Merge remote-tracking branch 'upstream/pr/1244'

* upstream/pr/1244:
  cmake: make package config relocatable

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3c99d61..5f054f3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -125,6 +125,9 @@
 include(CheckCXXCompilerFlag)
 include(AddCXXCompilerFlag)
 include(CXXFeatureCheck)
+include(CheckLibraryExists)
+
+check_library_exists(rt shm_open "" HAVE_LIB_RT)
 
 if (BENCHMARK_BUILD_32_BITS)
   add_required_cxx_compiler_flag(-m32)

cmake/Config.cmake.in

diff --git a/cmake/Config.cmake.in b/cmake/Config.cmake.in
index 6e9256e..0285a6c 100644
--- a/cmake/Config.cmake.in
+++ b/cmake/Config.cmake.in
@@ -1 +1,5 @@
+include (CMakeFindDependencyMacro)
+
+find_dependency (Threads)
+
 include("${CMAKE_CURRENT_LIST_DIR}/@targets_export_name@.cmake")

src/CMakeLists.txt

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0ee6836..e72c640 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -29,33 +29,28 @@
 
 # libpfm, if available
 if (HAVE_LIBPFM)
-  target_link_libraries(benchmark libpfm.a)
+  target_link_libraries(benchmark PRIVATE pfm)
   add_definitions(-DHAVE_LIBPFM)
 endif()
 
 # Link threads.
-target_link_libraries(benchmark  ${BENCHMARK_CXX_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT})
-find_library(LIBRT rt)
-if(LIBRT)
-  target_link_libraries(benchmark ${LIBRT})
-endif()
+target_link_libraries(benchmark PRIVATE Threads::Threads)
 
-if(CMAKE_BUILD_TYPE)
-  string(TOUPPER ${CMAKE_BUILD_TYPE} CMAKE_BUILD_TYPE_UPPER)
-endif()
-if(NOT CMAKE_THREAD_LIBS_INIT AND "${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${CMAKE_BUILD_TYPE_UPPER}}" MATCHES ".*-fsanitize=[^ ]*address.*")
-  message(WARNING "CMake's FindThreads.cmake did not fail, but CMAKE_THREAD_LIBS_INIT ended up being empty. This was fixed in https://github.com/Kitware/CMake/commit/d53317130e84898c5328c237186dbd995aaf1c12 Let's guess that -pthread is sufficient.")
-  target_link_libraries(benchmark -pthread)
-endif()
+target_link_libraries(benchmark PRIVATE ${BENCHMARK_CXX_LIBRARIES})
+
+if(HAVE_LIB_RT)
+  target_link_libraries(benchmark PRIVATE rt)
+endif(HAVE_LIB_RT)
+
 
 # We need extra libraries on Windows
 if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
-  target_link_libraries(benchmark shlwapi)
+  target_link_libraries(benchmark PRIVATE shlwapi)
 endif()
 
 # We need extra libraries on Solaris
 if(${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
-  target_link_libraries(benchmark kstat)
+  target_link_libraries(benchmark PRIVATE kstat)
 endif()
 
 # Benchmark main library