Add string duplication function (strdup)

src/String/String.c

@@ -0,0 +1,19 @@
+#include <BH/String.h>
+#include <string.h>
+#include <stdlib.h>
+
+
+char *BH_StringDup(const char *string)
+{
+    size_t length;
+    char *result;
+
+    if (!string)
+        return NULL;
+
+    length = strlen(string) + 1;
+    result = malloc(length);
+    if (result)
+        memcpy(result, string, length);
+    return result;
+}