Allow to use lld to link blobs

contrib/cctz-cmake/CMakeLists.txt

@@ -26,11 +26,15 @@ if (USE_INTERNAL_CCTZ)
 
     # Build a libray with embedded tzdata
 
-    # We invoke 'ld' and 'objcopy' directly because lld linker has no option to generate object file with binary data.
-    # Note: we can invoke specific ld from toolchain and relax condition on ARCH_AMD64.
-
     if (OS_LINUX AND ARCH_AMD64)
 
+        find_program (OBJCOPY_PATH NAMES "llvm-objcopy" "llvm-objcopy-10" "llvm-objcopy-9" "llvm-objcopy-8" "objcopy")
+        if (OBJCOPY_PATH)
+            message(STATUS "Using objcopy: ${OBJCOPY_PATH}.")
+        else ()
+            message(FATAL_ERROR "Cannot find objcopy.")
+        endif ()
+
         set (TIMEZONES
             Africa/Abidjan
             Africa/Accra
@@ -605,8 +609,8 @@ if (USE_INTERNAL_CCTZ)
 
             # https://stackoverflow.com/questions/14776463/compile-and-add-an-object-file-from-a-binary-with-cmake
             add_custom_command(OUTPUT ${TZ_OBJ}
-                COMMAND cd ${TZDIR} && ld -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/${TZ_OBJ} ${TIMEZONE}
-                COMMAND objcopy --rename-section .data=.rodata,alloc,load,readonly,data,contents
+                COMMAND cd ${TZDIR} && ${CMAKE_LINKER} -m elf_x86_64 -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/${TZ_OBJ} ${TIMEZONE}
+                COMMAND ${OBJCOPY_PATH} --rename-section .data=.rodata,alloc,load,readonly,data,contents
                     ${CMAKE_CURRENT_BINARY_DIR}/${TZ_OBJ} ${CMAKE_CURRENT_BINARY_DIR}/${TZ_OBJ})
 
             set_source_files_properties(${TZ_OBJ} PROPERTIES EXTERNAL_OBJECT true GENERATED true)