Support global variables in interop (#903)

backend.native/tests/interop/basics/cglobals.def

@@ -0,0 +1,28 @@
+---
+const int g1 = 42;
+
+int g2 = 17;
+
+struct S {
+    int x;
+} g3 = { 128 };
+
+int g4[2] = { 13, 14 };
+
+int g5[2][2] = { 15, 16, 17, 18 };
+
+struct S* const g6 = &g3;
+
+void foo() {
+    // Test that local vars are not treated as global ones.
+    float g1;
+}
+
+// Test non-compilable variable:
+typedef int MyInt;
+MyInt g7;
+#define g7 bad macro
+
+// Test property name mangling:
+struct g1 {};
+struct g1_ {};

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

@@ -0,0 +1,25 @@
+import kotlinx.cinterop.*
+import cglobals.*
+
+fun main(args: Array<String>) {
+    assert(g1__ == 42)
+
+    assert(g2 == 17)
+    g2 = 42
+    assert(g2 == 42)
+
+    assert(g3.x == 128)
+    g3.x = 7
+    assert(g3.x == 7)
+
+    assert(g4[1] == 14)
+    g4[1] = 15
+    assert(g4[1] == 15)
+
+    assert(g5[0] == 15)
+    assert(g5[3] == 18)
+    g5[0] = 16
+    assert(g5[0] == 16)
+
+    assert(g6 == g3.ptr)
+}