tinyglib: implement g_strdup

Fixes AddressSanitizer with SLiRP enabled.

src/include/tinyglib.h

@@ -215,6 +215,24 @@ g_strv_length(gchar **str_array)
 }
 
 
+/* Implementation borrowed from GLib itself. */
+static gchar*
+g_strdup(const gchar *str)
+{
+    gchar *new_str;
+    gsize length;
+
+    if (str) {
+	length = strlen(str) + 1;
+	new_str = malloc(sizeof(char) * length);
+	memcpy(new_str, str, length);
+    } else
+	new_str = NULL;
+
+    return new_str;
+}
+
+
 /* Macros */
 
 #define tinyglib_pclog(f, s, ...) pclog("TinyGLib " f "(): " s "\n", ##__VA_ARGS__)
@@ -271,7 +289,6 @@ g_strv_length(gchar **str_array)
 #define g_rand_free free
 #define g_realloc realloc
 #define g_snprintf snprintf
-#define g_strdup strdup
 #define g_strerror strerror
 #define g_strfreev free
 #define g_string_append_printf sprintf /* unimplemented */