boilerplate code to research string removal

research/strings_empty/tests/c_code.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main() {
+  printf("Hello, World!\n");
+  return 0;
+}

research/strings_empty/tests/objc_code.m

@@ -0,0 +1,8 @@
+#import <Foundation/Foundation.h>
+
+int main() {
+  @autoreleasepool {
+    NSLog(@"Hello, World!");
+  }
+  return 0;
+}

research/strings_empty/tests/swift_code.swift

@@ -0,0 +1 @@
+print("Hello, World!")