0.3.0: converge relibc to upstream 0.6.0 + Red Bear patches

tests/string/stpcpy.c

@@ -0,0 +1,26 @@
+#include <string.h>
+#include <assert.h>
+
+void test_stpcpy(const char *src, char *dest) {
+    char *end = stpcpy(dest, src);
+    assert(strcmp(dest, src) == 0);
+    assert(*end == '\0');
+    assert(end == dest + strlen(dest));
+}
+
+int main() {
+    char dest[20];
+
+    test_stpcpy("Hello, World!", dest);
+
+    // Test case 2: Empty string
+    test_stpcpy("", dest);
+
+    // Test case 3: String with special characters
+    test_stpcpy("Special chars: !@#$%^&*()", dest);
+
+    // Test case 4: String with spaces
+    test_stpcpy("A string with spaces", dest);
+
+    return 0;
+}