Win32: compatiblity with OpenSSL 1.1.0. OpenSSL 1.1.0 now uses normal "nmake; nmake install" instead of using custom "ms\do_ms.bat" script and "ms\nt.mak" makefile. And Configure now requires --prefix to be absolute, and no longer derives --openssldir from prefix (so it's specified explicitly). Generated libraries are now called "libcrypto.lib" and "libssl.lib" instead of "libeay32.lib" and "ssleay32.lib". Appropriate tests added to support both old and new variants. Additionally, openssl/lhash.h now triggers warning C4090 ('function' : different 'const' qualifiers), so the warning was disabled.

--- a/src/os/win32/ngx_win32_config.h
+++ b/src/os/win32/ngx_win32_config.h
@@ -88,6 +88,9 @@ typedef long  time_t;
 /* 'type cast': from data pointer to function pointer */
 #pragma warning(disable:4055)
 
+/* 'function' : different 'const' qualifiers */
+#pragma warning(disable:4090)
+
 /* unreferenced formal parameter */
 #pragma warning(disable:4100)