use correct definitions in debug mode with libc++ and libstdc++

- llvm suggest we should use _LIBCPP_HARDENING_MODE rather than
_LIBCPP_ENABLE_ASSERTIONS and they are about to remove
_LIBCPP_ENABLE_ASSERTIONS from llvm's sources at all, so we need to
prepare
- libstdc++ uses _GLIBCXX_ASSERTIONS, libc++ by llvm uses
_LIBCPP_HARDENING_MODE, so let's use them separately

Signed-off-by: Denis Pronin <dannftk@yandex.ru>

Author: dpronin

CMakeLists.txt

@@ -135,10 +135,26 @@ if(HAS_FCF_PROTECTION)
   target_compile_options(btop PRIVATE -fcf-protection)
 endif()
 
+check_cxx_source_compiles(
+  "
+  #include <algorithm>
+
+  #if !defined(__clang__) || !defined(_LIBCPP_VERSION)
+  # error \"This is not clang with libcxx by llvm\"
+  #endif
+
+  int main() {
+    return 0;
+  }
+  "
+  IS_CLANG_LIBCPP
+  FAIL_REGEX "This is not clang with libcxx by llvm"
+)
+
 target_compile_definitions(btop PRIVATE
   FMT_HEADER_ONLY
   _FILE_OFFSET_BITS=64
-  $<$<CONFIG:Debug>:_GLIBCXX_ASSERTIONS _LIBCPP_ENABLE_ASSERTIONS=1>
+  $<IF:$<AND:$<CONFIG:Debug>,$<BOOL:${IS_CLANG_LIBCPP}>>,_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_DEBUG,_GLIBCXX_ASSERTIONS>
   # Only has an effect with optimizations enabled
   $<$<AND:$<NOT:$<CONFIG:Debug>>,$<BOOL:${BTOP_FORTIFY}>>:_FORTIFY_SOURCE=3>
 )