Fix a grammatical error in crypto/openssl_util.h

crypto/openssl_util.h

Index: crypto/openssl_util.h
diff --git a/crypto/openssl_util.h b/crypto/openssl_util.h
index 3f89f9870240d646f0cae377d113eeb328bf2c1c..0d784a84842aad58bfb3b9fd64736d1202c32c0f 100644
--- a/crypto/openssl_util.h
+++ b/crypto/openssl_util.h
@@ -65,7 +65,7 @@ class ScopedOpenSSLSafeSizeBuffer {
   }
 
  private:
-  // Pointer to the caller's data area and it's associated size, where data
+  // Pointer to the caller's data area and its associated size, where data
   // written via safe_buffer() will [eventually] end up.
   unsigned char* output_;
   size_t output_len_;