SSL: avoid using OpenSSL config in build directory (ticket #2404). With this change, the NGX_OPENSSL_NO_CONFIG macro is defined when nginx is asked to build OpenSSL itself. And with this macro automatic loading of OpenSSL configuration (from the build directory) is prevented unless the OPENSSL_CONF environment variable is explicitly set. Note that not loading configuration is broken in OpenSSL 1.1.1 and 1.1.1a (fixed in OpenSSL 1.1.1b, see https://github.com/openssl/openssl/issues/7350). If nginx is used to compile these OpenSSL versions, configuring nginx with NGX_OPENSSL_NO_CONFIG explicitly set to 0 might be used as a workaround.

--- a/auto/lib/openssl/conf
+++ b/auto/lib/openssl/conf
@@ -8,6 +8,8 @@ if [ $OPENSSL != NONE ]; then
     have=NGX_OPENSSL . auto/have
     have=NGX_SSL . auto/have
 
+    have=NGX_OPENSSL_NO_CONFIG . auto/have
+
     if [ $USE_OPENSSL_QUIC = YES ]; then
         have=NGX_QUIC . auto/have
         have=NGX_QUIC_OPENSSL_COMPAT . auto/have