build: got rid of old clang hacks and range-v3 dependency

src/cmake/CheckLibcxxInUse.cmake

@@ -1,41 +0,0 @@
-# The MIT License (MIT)
-#
-# Copyright (c) 2018 Mateusz Pusz
-#
-# Permission is hereby granted, free of charge, to any person obtaining a copy
-# of this software and associated documentation files (the "Software"), to deal
-# in the Software without restriction, including without limitation the rights
-# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-# copies of the Software, and to permit persons to whom the Software is
-# furnished to do so, subject to the following conditions:
-#
-# The above copyright notice and this permission notice shall be included in all
-# copies or substantial portions of the Software.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-# SOFTWARE.
-
-cmake_minimum_required(VERSION 3.15)
-
-function(check_libcxx_in_use variable)
-    if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-        message(CHECK_START "Checking if libc++ is being used")
-        list(APPEND CMAKE_MESSAGE_INDENT "  ")
-
-        include(CheckCXXSymbolExists)
-        check_cxx_symbol_exists(_LIBCPP_VERSION "ciso646" ${variable})
-        set(${variable} ${${variable}} PARENT_SCOPE)
-
-        list(POP_BACK CMAKE_MESSAGE_INDENT)
-        if(${variable})
-            message(CHECK_PASS "found")
-        else()
-            message(CHECK_FAIL "not found")
-        endif()
-    endif()
-endfunction()