Fix MSVC level 1 (severe) warnings

We fix (hopefully) all instances of:

* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4005>
* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4024>
* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4028>
* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4047>
* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4087>
* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4090>
* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4273>
* <https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4312>

`zend_llist_add_element()` and `zend_llist_prepend_element()` now
explicitly expect a *const* pointer.

We use the macro `ZEND_VOIDP()` instead of a `(void*)` cast to suppress
C4090; this should prevent accidential removal of the cast by
clarifying the intention, and makes it easier to remove the casts if
the issue[1] will be resolved sometime.

[1] <https://developercommunity.visualstudio.com/content/problem/390711/c-compiler-incorrect-propagation-of-const-qualifie.html>

1 files changed, 1 insertions, 1 deletions

diff --git a/ext/mysqlnd/mysqlnd_auth.c b/ext/mysqlnd/mysqlnd_auth.c
index e947e4b253..81700ca86b 100644
--- a/ext/mysqlnd/mysqlnd_auth.c
+++ b/ext/mysqlnd/mysqlnd_auth.c
@@ -752,7 +752,7 @@ static mysqlnd_rsa_t
 mysqlnd_sha256_get_rsa_from_pem(const char *buf, size_t len)
 {
 	BCRYPT_KEY_HANDLE ret = 0;
-	LPCSTR der_buf = NULL;
+	LPSTR der_buf = NULL;
 	DWORD der_len;
 	CERT_PUBLIC_KEY_INFO *key_info = NULL;
 	DWORD key_info_len;