Version identifier cpp -> LLVM/GNU, see dlang/dmd#16613 (#3853)

Version identifier cpp -> LLVM/GNU, see dlang/dmd#16613

Signed-off-by: Iain Buclaw <ibuclaw@users.noreply.github.com>
Merged-on-behalf-of: Iain Buclaw <ibuclaw@users.noreply.github.com>

Author: JohanEngelen

spec/version.dd

@@ -257,11 +257,11 @@ $(H3 $(LEGACY_LNAME2 PredefinedVersions, predefined-versions, Predefined Version
         $(TROW $(ARGS $(D CRuntime_Newlib)) , $(ARGS newlib C runtime))
         $(TROW $(ARGS $(D CRuntime_UClibc)) , $(ARGS uClibc C runtime))
         $(TROW $(ARGS $(D CRuntime_WASI)) , $(ARGS WASI C runtime))
-        $(TROW $(ARGS $(D CppRuntime_Clang)) , $(ARGS Deprecated, use $(D CppRuntime_libcpp) instead))
+        $(TROW $(ARGS $(D CppRuntime_Clang)) , $(ARGS Deprecated, use $(D CppRuntime_LLVM) instead))
         $(TROW $(ARGS $(D CppRuntime_DigitalMars)) , $(ARGS DigitalMars C++ runtime))
-        $(TROW $(ARGS $(D CppRuntime_Gcc)) , $(ARGS Deprecated, use $(D CppRuntime_libstdcpp) instead))
-        $(TROW $(ARGS $(D CppRuntime_libcpp)) , $(ARGS libc++ C++ runtime))
-        $(TROW $(ARGS $(D CppRuntime_libstdcpp)) , $(ARGS libstdc++ C++ runtime))
+        $(TROW $(ARGS $(D CppRuntime_Gcc)) , $(ARGS Deprecated, use $(D CppRuntime_GNU) instead))
+        $(TROW $(ARGS $(D CppRuntime_LLVM)) , $(ARGS LLVM libc++ C++ runtime))
+        $(TROW $(ARGS $(D CppRuntime_GNU)) , $(ARGS GNU libstdc++ C++ runtime))
         $(TROW $(ARGS $(D CppRuntime_Microsoft)) , $(ARGS Microsoft C++ runtime))
         $(TROW $(ARGS $(D CppRuntime_Sun)) , $(ARGS Sun C++ runtime))
         $(TROW $(ARGS $(D X86)) , $(ARGS Intel and AMD 32-bit processors))