move c++ demo in separate file

add newline to printf

demos/c++/c.cpp

@@ -0,0 +1,8 @@
+#include <iostream>
+
+extern void foo();
+
+int main() {
+	printf("%s\n", HELLO_WORLD);
+	return 0;
+}

demos/c++/main.cpp

@@ -4,6 +4,5 @@ extern void foo();
 
 int main() {
 	foo();
-	printf("%s", HELLO_WORLD);
 	return 0;
 }

demos/c++/wscript

@@ -21,8 +21,9 @@ def build(bld):
 	bld.shlib(source='a.cpp', target='mylib', vnum='9.8.7')
 	bld.shlib(source='a.cpp', target='mylib2', vnum='9.8.7', cnum='9.8')
 	bld.shlib(source='a.cpp', target='mylib3')
-	bld.program(source='main.cpp', target='app', include_files='file-include/inc-file/header.h', use='mylib')
+	bld.program(source='main.cpp', target='app', use='mylib')
 	bld.stlib(target='foo', source='b.cpp')
+	bld.program(source='c.cpp', target='file-include', include_files='file-include/inc-file/header.h', use='mylib')
 
 	# just a test to check if the .c is compiled as c++ when no c compiler is found
 	bld.program(features='cxx cxxprogram', source='main.c', target='app2')

demos/c/file-include/main.c

@@ -2,6 +2,6 @@
 
 int main()
 {
-	printf("%s", HELLO_WORLD);
+	printf("%s\n", HELLO_WORLD);
 	return 0;
 }