Change test app to C++ for better check on naming

linker/tests/Makefile

@@ -1,10 +1,10 @@
 all: platform
 
-platform: platform.c libapp.so
-	$(CC) -O2 -fPIC -fPIE -o $@ $^
+platform: platform.cc libapp.so
+	$(CXX) -O2 -fPIC -fPIE -o $@ $^
 
-libapp.so: app.c
-	$(CC) -O2 -fPIC -shared -o $@ $^
+libapp.so: app.cc
+	$(CXX) -O2 -fPIC -shared -o $@ $^
 
 clean:
-	rm -f platform libapp.so
+	rm -f platform libapp.so

linker/tests/app.c

@@ -1,3 +0,0 @@
-#include <stdio.h>
-
-void app() { printf("Hello World from the application"); }

linker/tests/app.cc

@@ -0,0 +1,3 @@
+#include <iostream>
+
+void app() { std::cout << "Hello World from the application" << std::endl; }

linker/tests/platform.c

@@ -1,9 +0,0 @@
-#include <stdio.h>
-
-void app();
-
-int main() {
-  printf("Hello World from the platform");
-  app();
-  return 0;
-}

linker/tests/platform.cc

@@ -0,0 +1,9 @@
+#include <iostream>
+
+void app();
+
+int main() {
+  std::cout << "Hello World from the platform\n";
+  app();
+  return 0;
+}