Fix TCC compilation

Author: hirrolot

tests/basic_tests.c

@@ -116,4 +116,6 @@ int main(void) {
         assert(((TestCompoundLit *)compound.self)->d == 15);
         assert(strcmp(((TestCompoundLit *)compound.self)->str, "abc") == 0);
     }
+
+    return 0;
 }

tests/decl_impl.c

@@ -25,4 +25,6 @@ declImpl(Bar, BarImpl);
 
 int main(void) {
     test_decl_impl();
+
+    return 0;
 }

tests/default_impl.c

@@ -49,4 +49,6 @@ int main(void) {
     assert(VTABLE(A, TestDefault).default_op == TestDefault_default_op);
     assert(VTABLE(B, TestDefault).default_op == custom_impl);
     assert(VTABLE(C, TestNoOpCustom).custom_op == custom_impl);
+
+    return 0;
 }

tests/extern_impl/test.c

@@ -21,4 +21,6 @@ int main(void) {
 
     ENSURE_DYN_OBJ(FooImpl, Foo);
     ENSURE_DYN_OBJ(BarImpl, Bar);
+
+    return 0;
 }

tests/metalang99_compliant.c

@@ -47,4 +47,6 @@ int main(void) {
 
     ENSURE_DYN_OBJ(A, Foo);
     ENSURE_DYN_OBJ(B, Foo);
+
+    return 0;
 }

tests/superinterfaces.c

@@ -132,4 +132,6 @@ int main(void) {
         ENSURE_DYN_OBJ(D, Foo);
         ENSURE_DYN_OBJ(D, Bar);
     }
+
+    return 0;
 }

tests/vcalls.c

@@ -105,4 +105,6 @@ int main(void) {
     }
 
 #undef RVALUE
+
+    return 0;
 }

tests/version.c

@@ -48,4 +48,6 @@ int main(void) {
 #undef IFACE99_MAJOR
 #undef IFACE99_MINOR
 #undef IFACE99_PATCH
+
+    return 0;
 }