[K/N] Introduce ClangArgs.clangArgsForKonan(C|Cxx)Sources

There is `ClangArgs.clangArgsForKonanSources`, but it is specific to
C++ (clang++) and fails to mention this in the name.

This commit introduces two other properties to support the C case and
make the distinction clear.

It also makes public the language-agnostic part,
`ClangArgs.clangArgsSpecificForKonanSources`, just to make things more
flexible.

Author: SvyatoslavScherbina

native/utils/src/org/jetbrains/kotlin/konan/target/ClangArgs.kt

@@ -34,7 +34,7 @@ sealed class ClangArgs(
     // TODO: Should be dropped in favor of real MSVC target.
     private val argsForWindowsJni = forJni && target == KonanTarget.MINGW_X64
 
-    private val clangArgsSpecificForKonanSources : List<String>
+    val clangArgsSpecificForKonanSources: List<String>
         get() {
             val konanOptions = listOfNotNull(
                     target.architecture.name.takeIf { target != KonanTarget.WATCHOS_ARM64 },
@@ -169,9 +169,16 @@ sealed class ClangArgs(
         else -> emptyArray()
     }
 
+    // Kept for compatibility, remove later.
     val clangArgsForKonanSources =
             clangXXArgs + clangArgsSpecificForKonanSources
 
+    val clangArgsForKonanCxxSources =
+            (clangXXArgs + clangArgsSpecificForKonanSources).asList()
+
+    val clangArgsForKonanCSources =
+            (clangArgs + clangArgsSpecificForKonanSources).asList()
+
     private val libclangSpecificArgs =
             // libclang works not exactly the same way as the clang binary and
             // (in particular) uses different default header search path.