Handle Linux systems that use /lib64 instead of /lib

Use CMAKE_INSTALL_LIBDIR variable to set the correct lib folder to use
for installing libraries so that CMake looks in the right place for the
dependencies when linking

cmake/BuildCTranslate2.cmake

@@ -72,7 +72,7 @@ else()
     BUILD_COMMAND ${CMAKE_COMMAND} --build <BINARY_DIR> --config ${CMAKE_BUILD_TYPE}
     CMAKE_GENERATOR ${CMAKE_GENERATOR}
     INSTALL_COMMAND ${CMAKE_COMMAND} --install <BINARY_DIR> --config ${CMAKE_BUILD_TYPE}
-    BUILD_BYPRODUCTS <INSTALL_DIR>/lib/${CMAKE_STATIC_LIBRARY_PREFIX}cpu_features${CMAKE_STATIC_LIBRARY_SUFFIX}
+    BUILD_BYPRODUCTS <INSTALL_DIR>/${CMAKE_INSTALL_LIBDIR}/${CMAKE_STATIC_LIBRARY_PREFIX}cpu_features${CMAKE_STATIC_LIBRARY_SUFFIX}
     CMAKE_ARGS -DCMAKE_GENERATOR_PLATFORM=${CMAKE_GENERATOR_PLATFORM} -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
                -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE} ${CPU_FEATURES_CMAKE_ARGS}
     LOG_CONFIGURE ON
@@ -84,7 +84,7 @@ else()
   add_dependencies(cpu_features cpu_features_build)
   set_target_properties(
     cpu_features PROPERTIES IMPORTED_LOCATION
-                            ${INSTALL_DIR}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}cpu_features${CMAKE_STATIC_LIBRARY_SUFFIX})
+                            ${INSTALL_DIR}/${CMAKE_INSTALL_LIBDIR}/${CMAKE_STATIC_LIBRARY_PREFIX}cpu_features${CMAKE_STATIC_LIBRARY_SUFFIX})
   set_target_properties(cpu_features PROPERTIES INTERFACE_INCLUDE_DIRECTORIES ${INSTALL_DIR}/include)
 
   # build CTranslate2 from source
@@ -93,7 +93,7 @@ else()
   set(CT2_OPENBLAS_CMAKE_ARGS -DWITH_OPENBLAS=OFF)
 
   set(CT2_CMAKE_PLATFORM_OPTIONS -DBUILD_SHARED_LIBS=OFF -DOPENMP_RUNTIME=NONE -DCMAKE_POSITION_INDEPENDENT_CODE=ON)
-  set(CT2_LIB_INSTALL_LOCATION lib/${CMAKE_SHARED_LIBRARY_PREFIX}ctranslate2${CMAKE_STATIC_LIBRARY_SUFFIX})
+  set(CT2_LIB_INSTALL_LOCATION ${CMAKE_INSTALL_LIBDIR}/${CMAKE_SHARED_LIBRARY_PREFIX}ctranslate2${CMAKE_STATIC_LIBRARY_SUFFIX})
 
   ExternalProject_Add(
     ct2_build

cmake/BuildSentencepiece.cmake

@@ -32,7 +32,7 @@ else()
       CACHE STRING "URL of sentencepiece repository")
 
   set(SP_CMAKE_OPTIONS -DSPM_ENABLE_SHARED=OFF)
-  set(SENTENCEPIECE_INSTALL_LIB_LOCATION lib/${CMAKE_STATIC_LIBRARY_PREFIX}sentencepiece${CMAKE_STATIC_LIBRARY_SUFFIX})
+  set(SENTENCEPIECE_INSTALL_LIB_LOCATION ${CMAKE_INSTALL_LIBDIR}/${CMAKE_STATIC_LIBRARY_PREFIX}sentencepiece${CMAKE_STATIC_LIBRARY_SUFFIX})
 
   include(ExternalProject)