Make build reproducible on macOS & modernize CMake

 - Use target properties
   - More robust/easier/transitive usage
   - More robust/easier CMake config files for use with
     `find_package(OPENCOARRAYS)`
 - Make builds reproducible when:
   - `ZERO_AR_DATE=1`
   - `SOURCE_DATE_EPOCH=<unix time of last commit>`
   - Modules not checked/verified, these may also be needed:
     - Source/build directory:
       - `/Users/ibeekman/Sandbox/OpenCoarrays{,/build}`
     - `LC_ALL=C`
     - `TZ=UTC`

Author: zbeekman

CMakeLists.txt

@@ -1,7 +1,13 @@
 cmake_minimum_required(VERSION 3.10)
 
-cmake_policy(VERSION 3.10...3.12)
-
+cmake_policy(VERSION 3.10...3.14)
+
+set(CMAKE_SKIP_RPATH ON
+  CACHE BOOL "Don't add a build-dir rpath")
+set(CMAKE_BUILD_WITH_INSTALL_RPATH ON
+  CACHE BOOL "Build using the install rpath")
+set(CMAKE_BUILD_RPATH_USE_ORIGIN ON
+  CACHE BOOL "Use relative rpaths")
 # Set the type/configuration of build to perform
 set ( CMAKE_CONFIGURATION_TYPES "Debug" "Release" "MinSizeRel" "RelWithDebInfo" "CodeCoverage" )
 set ( CMAKE_BUILD_TYPE "Release"
@@ -88,6 +94,11 @@ string(REGEX REPLACE "-rc[0-9]+$"
 
 project(opencoarrays VERSION "${OPENCOARRAYS_CMAKE_PROJECT_VERSION}" LANGUAGES C Fortran)
 
+if(DEFINED CMAKE_BUILD_TYPE AND "${CMAKE_BUILD_TYPE}" MATCHES "[Rr][Ee][Ll]")
+  set(CMAKE_Fortran_FLAGS "${CMAKE_Fortran_FLAGS} -fno-working-directory")
+  set(CMAKE_C_FLAGS       "${CMAKE_C_FLAGS} -fno-working-directory")
+endif()
+
 message( STATUS "Building OpenCoarrays version: ${full_git_describe}" )
 set(OpenCoarrays_dist_string "OpenCoarrays-${full_git_describe}")
 message( STATUS "Building for target architecture: ${CMAKE_SYSTEM_PROCESSOR}" )
@@ -483,7 +494,6 @@ set(CMAKE_C_COMPILE_FLAGS "${CMAKE_C_COMPILE_FLAGS} ${MPI_C_COMPILE_FLAGS}")
 set(CMAKE_C_LINK_FLAGS "${CMAKE_C_LINK_FLAGS} ${MPI_C_LINK_FLAGS}")
 set(CMAKE_Fortran_COMPILE_FLAGS "${CMAKE_Fortran_COMPILE_FLAGS} ${MPI_Fortran_COMPILE_FLAGS}")
 set(CMAKE_Fortran_LINK_FLAGS "${CMAKE_Fortran_LINK_FLAGS} ${MPI_Fortran_LINK_FLAGS}")
-include_directories(BEFORE ${MPI_C_INCLUDE_PATH} ${MPI_Fortran_INCLUDE_PATH})
 
 #---------------------------------------------------
 # Use standardized GNU install directory conventions
@@ -591,8 +601,6 @@ define_property(TARGET
 #-------------------------------
 # Recurse into the src directory
 #-------------------------------
-include_directories(BEFORE ${CMAKE_CURRENT_SOURCE_DIR}/src)
-
 add_subdirectory(src)
 
 #-----------------------------------------------------

src/mpi/CMakeLists.txt

@@ -26,8 +26,10 @@ target_compile_options(opencoarrays_mod
 target_link_libraries(opencoarrays_mod
   PUBLIC ${MPI_Fortran_LINK_FLAGS}
   PUBLIC ${MPI_Fortran_LIBRARIES})
-target_include_directories(opencoarrays_mod
-  PRIVATE $<$<COMPILE_LANGUAGE:Fortran>:${MPI_Fortran_INCLUDE_PATH}>)
+target_include_directories(opencoarrays_mod PUBLIC
+  $<$<COMPILE_LANGUAGE:Fortran>:${MPI_Fortran_INCLUDE_PATH}>
+  $<BUILD_INTERFACE:${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_INCLUDEDIR}/${mod_dir_tail}>
+  $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/${mod_dir_tail}>)
 
 add_library(caf_mpi SHARED mpi_caf.c ../common/caf_auxiliary.c)
 add_library(caf_mpi_static STATIC  mpi_caf.c ../common/caf_auxiliary.c)
@@ -42,10 +44,14 @@ target_link_libraries(caf_mpi_static
 set_target_properties(caf_mpi_static
   PROPERTIES
   POSITION_INDEPENDENT_CODE TRUE)
-target_include_directories(caf_mpi
-  PUBLIC $<$<COMPILE_LANGUAGE:C>:${MPI_C_INCLUDE_PATH}>)
-target_include_directories(caf_mpi_static
-  PUBLIC $<$<COMPILE_LANGUAGE:C>:${MPI_C_INCLUDE_PATH}>)
+target_include_directories(caf_mpi PUBLIC
+  $<$<COMPILE_LANGUAGE:C>:${MPI_C_INCLUDE_PATH}>
+  $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/src>
+  $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
+target_include_directories(caf_mpi_static PUBLIC
+  $<$<COMPILE_LANGUAGE:C>:${MPI_C_INCLUDE_PATH}>
+  $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/src>
+  $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
 target_compile_options(caf_mpi
   PUBLIC $<$<COMPILE_LANGUAGE:C>:${MPI_C_COMPILE_FLAGS}>)
 target_compile_options(caf_mpi_static