CMake: fix winsock2 detection on windows

Set CMAKE_REQUIRED_DEFINITIONS to include definitions needed to get
the winsock2 API from windows.h.  Simplify the order of checks to
avoid extra conditions.

Use check_include_file instead of check_include_file_concat to look
for OpenSSL headers.  They do not need to participate in a sequence
of dependent system headers.  Also they may cause winsock.h to be
included before ws2tcpip.h, causing the latter to not be detected
in the sequence.

Reviewed-by: Brad King <brad.king@kitware.com>

CMake/FindGSS.cmake

@@ -155,7 +155,7 @@ message(STATUS "LDFLAGS: ${_GSS_LIB_FLAGS}")
                 set(GSS_FLAVOUR "MIT")
             else()
                 # prevent compiling the header - just check if we can include it
-                set(CMAKE_REQUIRED_DEFINITIONS "-D__ROKEN_H__")
+                set(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS} -D__ROKEN_H__")
                 check_include_file( "roken.h" _GSS_HAVE_ROKEN_H)
 
                 check_include_file( "heimdal/roken.h" _GSS_HAVE_HEIMDAL_ROKEN_H)

CMakeLists.txt

@@ -238,6 +238,7 @@ include (CheckCSourceCompiles)
 
 # On windows preload settings
 if(WIN32)
+  set(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS} -D_WINSOCKAPI_")
   include(${CMAKE_CURRENT_SOURCE_DIR}/CMake/Platforms/WindowsCache.cmake)
 endif(WIN32)
 
@@ -294,15 +295,15 @@ if(CMAKE_USE_OPENSSL)
     set(HAVE_LIBSSL ON)
     include_directories(${OPENSSL_INCLUDE_DIR})
     set(CMAKE_REQUIRED_INCLUDES ${OPENSSL_INCLUDE_DIR})
-    check_include_file_concat("openssl/crypto.h" HAVE_OPENSSL_CRYPTO_H)
-    check_include_file_concat("openssl/engine.h" HAVE_OPENSSL_ENGINE_H)
-    check_include_file_concat("openssl/err.h"    HAVE_OPENSSL_ERR_H)
-    check_include_file_concat("openssl/pem.h"    HAVE_OPENSSL_PEM_H)
-    check_include_file_concat("openssl/pkcs12.h" HAVE_OPENSSL_PKCS12_H)
-    check_include_file_concat("openssl/rsa.h"    HAVE_OPENSSL_RSA_H)
-    check_include_file_concat("openssl/ssl.h"    HAVE_OPENSSL_SSL_H)
-    check_include_file_concat("openssl/x509.h"   HAVE_OPENSSL_X509_H)
-    check_include_file_concat("openssl/rand.h"   HAVE_OPENSSL_RAND_H)
+    check_include_file("openssl/crypto.h" HAVE_OPENSSL_CRYPTO_H)
+    check_include_file("openssl/engine.h" HAVE_OPENSSL_ENGINE_H)
+    check_include_file("openssl/err.h"    HAVE_OPENSSL_ERR_H)
+    check_include_file("openssl/pem.h"    HAVE_OPENSSL_PEM_H)
+    check_include_file("openssl/pkcs12.h" HAVE_OPENSSL_PKCS12_H)
+    check_include_file("openssl/rsa.h"    HAVE_OPENSSL_RSA_H)
+    check_include_file("openssl/ssl.h"    HAVE_OPENSSL_SSL_H)
+    check_include_file("openssl/x509.h"   HAVE_OPENSSL_X509_H)
+    check_include_file("openssl/rand.h"   HAVE_OPENSSL_RAND_H)
   endif()
 endif()
 
@@ -384,7 +385,7 @@ if(NOT CURL_DISABLE_LDAP)
         return 0;
       }"
     )
-    set(CMAKE_REQUIRED_DEFINITIONS "-DLDAP_DEPRECATED=1" "-DWIN32_LEAN_AND_MEAN")
+    set(CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS} -DLDAP_DEPRECATED=1")
     list(APPEND CMAKE_REQUIRED_LIBRARIES ${CMAKE_LDAP_LIB})
     if(HAVE_LIBLBER)
       list(APPEND CMAKE_REQUIRED_LIBRARIES ${CMAKE_LBER_LIB})
@@ -537,15 +538,13 @@ endif()
 
 # Check for header files
 if(NOT UNIX)
+  check_include_file_concat("windows.h"      HAVE_WINDOWS_H)
+  check_include_file_concat("winsock.h"      HAVE_WINSOCK_H)
   check_include_file_concat("ws2tcpip.h"     HAVE_WS2TCPIP_H)
   check_include_file_concat("winsock2.h"     HAVE_WINSOCK2_H)
 endif(NOT UNIX)
-check_include_file_concat("stdio.h"          HAVE_STDIO_H)
-if(NOT UNIX)
-  check_include_file_concat("windows.h"      HAVE_WINDOWS_H)
-  check_include_file_concat("winsock.h"      HAVE_WINSOCK_H)
-endif(NOT UNIX)
 
+check_include_file_concat("stdio.h"          HAVE_STDIO_H)
 check_include_file_concat("inttypes.h"       HAVE_INTTYPES_H)
 check_include_file_concat("sys/filio.h"      HAVE_SYS_FILIO_H)
 check_include_file_concat("sys/ioctl.h"      HAVE_SYS_IOCTL_H)