[openmp][cmake] Use `GNUInstallDirs` to support custom installation dirs

I am breaking apart D99484 so the cause of build failures is easier to
understand.

Differential Revision: https://reviews.llvm.org/D117945

openmp/CMakeLists.txt

@@ -7,7 +7,12 @@ set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
 if (OPENMP_STANDALONE_BUILD OR "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
   set(OPENMP_STANDALONE_BUILD TRUE)
   project(openmp C CXX)
+endif()
+
+# Must go below project(..)
+include(GNUInstallDirs)
 
+if (OPENMP_STANDALONE_BUILD)
   # CMAKE_BUILD_TYPE was not set, default to Release.
   if (NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE Release)

openmp/libompd/src/CMakeLists.txt

@@ -47,4 +47,4 @@ include_directories (
 INSTALL( TARGETS ompd
         LIBRARY DESTINATION ${OPENMP_INSTALL_LIBDIR}
         ARCHIVE DESTINATION ${OPENMP_INSTALL_LIBDIR}
-        RUNTIME DESTINATION bin )
+        RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" )

openmp/runtime/cmake/LibompCheckLinkerFlag.cmake

@@ -8,6 +8,8 @@
 #//===----------------------------------------------------------------------===//
 #
 
+include(GNUInstallDirs)
+
 # Checking a linker flag to build a shared library
 # There is no real trivial way to do this in CMake, so we implement it here
 # this will have ${boolean} = TRUE if the flag succeeds, otherwise FALSE.

openmp/runtime/src/CMakeLists.txt

@@ -346,19 +346,19 @@ add_dependencies(libomp-micro-tests libomp-test-deps)
 # We want to install libomp in DESTDIR/CMAKE_INSTALL_PREFIX/lib
 # We want to install headers in DESTDIR/CMAKE_INSTALL_PREFIX/include
 if(${OPENMP_STANDALONE_BUILD})
-  set(LIBOMP_HEADERS_INSTALL_PATH include)
+  set(LIBOMP_HEADERS_INSTALL_PATH "${CMAKE_INSTALL_INCLUDEDIR}")
 else()
   string(REGEX MATCH "[0-9]+\\.[0-9]+(\\.[0-9]+)?" CLANG_VERSION ${PACKAGE_VERSION})
   set(LIBOMP_HEADERS_INSTALL_PATH "${OPENMP_INSTALL_LIBDIR}/clang/${CLANG_VERSION}/include")
 endif()
 if(WIN32)
-  install(TARGETS omp RUNTIME DESTINATION bin)
+  install(TARGETS omp RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
   install(TARGETS ${LIBOMP_IMP_LIB_TARGET} ARCHIVE DESTINATION "${OPENMP_INSTALL_LIBDIR}")
   # Create aliases (regular copies) of the library for backwards compatibility
   set(LIBOMP_ALIASES "libiomp5md")
   foreach(alias IN LISTS LIBOMP_ALIASES)
     install(CODE "execute_process(COMMAND \"\${CMAKE_COMMAND}\" -E copy \"${LIBOMP_LIB_FILE}\"
-      \"${alias}${LIBOMP_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \"\${CMAKE_INSTALL_PREFIX}/bin\")")
+      \"${alias}${LIBOMP_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \"\${CMAKE_INSTALL_BINDIR}\")")
     install(CODE "execute_process(COMMAND \"\${CMAKE_COMMAND}\" -E copy \"${LIBOMP_IMP_LIB_FILE}\"
       \"${alias}${CMAKE_STATIC_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \"\${CMAKE_INSTALL_PREFIX}/${OPENMP_INSTALL_LIBDIR}\")")
   endforeach()

openmp/tools/multiplex/CMakeLists.txt

@@ -4,7 +4,7 @@ if(LIBOMP_OMPT_SUPPORT)
   add_library(ompt-multiplex INTERFACE)
   target_include_directories(ompt-multiplex INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
 
-  install(FILES ompt-multiplex.h DESTINATION include)
+  install(FILES ompt-multiplex.h DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
 
   add_subdirectory(tests)
 endif()