Added submodule contents into tree

externals/mbedtls/programs/fuzz/fuzz_pkcs7.c

@@ -0,0 +1,20 @@
+#include <stdint.h>
+#include "mbedtls/pkcs7.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
+{
+#ifdef MBEDTLS_PKCS7_C
+    mbedtls_pkcs7 pkcs7;
+
+    mbedtls_pkcs7_init(&pkcs7);
+
+    mbedtls_pkcs7_parse_der(&pkcs7, Data, Size);
+
+    mbedtls_pkcs7_free(&pkcs7);
+#else
+    (void) Data;
+    (void) Size;
+#endif
+
+    return 0;
+}