Simplify working with values in interop

* Access primitive interop array elements and struct fields without `.value`
* Simplify C*Var* interop types names

backend.native/tests/interop/basics/0.kt

@@ -5,5 +5,5 @@ fun main(args: Array<String>) {
     val statBuf = nativeHeap.alloc<statStruct>()
     val res = stat("/", statBuf.ptr)
     println(res)
-    println(statBuf.st_uid.value)
+    println(statBuf.st_uid)
 }

backend.native/tests/interop/basics/3.kt

@@ -4,17 +4,17 @@ fun main(args: Array<String>) {
     memScoped {
         val count = 5
 
-        val values = allocArray<CInt32Var>(count)
-        values[0].value = 14
-        values[1].value = 12
-        values[2].value = 9
-        values[3].value = 13
-        values[4].value = 8
+        val values = allocArray<IntVar>(count)
+        values[0] = 14
+        values[1] = 12
+        values[2] = 9
+        values[3] = 13
+        values[4] = 8
 
-        cstdlib.qsort(values, count.toLong(), CInt32Var.size, staticCFunction(::comparator))
+        cstdlib.qsort(values, count.toLong(), IntVar.size, staticCFunction(::comparator))
 
         for (i in 0 .. count - 1) {
-            print(values[i].value)
+            print(values[i])
             print(" ")
         }
         println()
@@ -22,8 +22,8 @@ fun main(args: Array<String>) {
 }
 
 private fun comparator(a: COpaquePointer?, b: COpaquePointer?): Int {
-    val aValue = a!!.reinterpret<CInt32Var>().pointed.value
-    val bValue = b!!.reinterpret<CInt32Var>().pointed.value
+    val aValue = a!!.reinterpret<IntVar>()[0]
+    val bValue = b!!.reinterpret<IntVar>()[0]
 
     return (aValue - bValue)
 }

backend.native/tests/interop/basics/4.kt

@@ -6,8 +6,8 @@ fun main(args: Array<String>) {
             "a", "b".cstr, (-1).toByte(), 2.toShort(), 3, Long.MAX_VALUE, 0.1.toFloat(), 0.2)
 
     memScoped {
-        val aVar = alloc<CInt32Var>()
-        val bVar = alloc<CInt32Var>()
+        val aVar = alloc<IntVar>()
+        val bVar = alloc<IntVar>()
         val sscanfResult = sscanf("42", "%d%d", aVar.ptr, bVar.ptr)
         printf("%d %d\n", sscanfResult, aVar.value)
     }

backend.native/tests/interop/basics/echo_server.kt

@@ -12,7 +12,7 @@ fun main(args: Array<String>) {
     memScoped {
 
         val bufferLength = 100L
-        val buffer = allocArray<CInt8Var>(bufferLength)
+        val buffer = allocArray<ByteVar>(bufferLength)
         val serverAddr = alloc<sockaddr_in>()
 
         val listenFd = socket(AF_INET, SOCK_STREAM, 0)
@@ -20,9 +20,9 @@ fun main(args: Array<String>) {
 
         with(serverAddr) {
             memset(this.ptr, 0, sockaddr_in.size)
-            sin_family.value = AF_INET.narrow()
-            sin_addr.s_addr.value = htons(0).toInt()
-            sin_port.value = htons(port)
+            sin_family = AF_INET.narrow()
+            sin_addr.s_addr = htons(0).toInt()
+            sin_port = htons(port)
         }
 
         bind(listenFd, serverAddr.ptr.reinterpret(), sockaddr_in.size.toInt())

backend.native/tests/interop/basics/opengl_teapot.kt

@@ -83,7 +83,7 @@ fun initialize() {
 fun main(args: Array<String>) {
     // initialize and run program
     memScoped {
-        val argc = alloc<CInt32Var>().apply { value = 0 }
+        val argc = alloc<IntVar>().apply { value = 0 }
         glutInit(argc.ptr, null) // TODO: pass real args
     }