CMake corrections for building on Windows (#1122)

* Replace use of newer CMake builtins than in v3.0.0

Visual Studio generator will replace -D with /D.

* Only use /Z7 flag on a Visual Studio compilator

Flag is not available on a GNU compilator running on windows,
like in a mingw64 setup.

Author: bjosv

CMakeLists.txt

@@ -41,7 +41,7 @@ SET(hiredis_sources
 SET(hiredis_sources ${hiredis_sources})
 
 IF(WIN32)
-    ADD_COMPILE_DEFINITIONS(_CRT_SECURE_NO_WARNINGS WIN32_LEAN_AND_MEAN)
+    ADD_DEFINITIONS(-D_CRT_SECURE_NO_WARNINGS -DWIN32_LEAN_AND_MEAN)
 ENDIF()
 
 ADD_LIBRARY(hiredis SHARED ${hiredis_sources})
@@ -57,7 +57,7 @@ ENDIF()
 SET_TARGET_PROPERTIES(hiredis
     PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS TRUE
     VERSION "${HIREDIS_SONAME}")
-IF(WIN32)
+IF(MSVC)
     SET_TARGET_PROPERTIES(hiredis_static
         PROPERTIES COMPILE_FLAGS /Z7)
 ENDIF()
@@ -178,7 +178,7 @@ IF(ENABLE_SSL)
         PROPERTIES
         WINDOWS_EXPORT_ALL_SYMBOLS TRUE
         VERSION "${HIREDIS_SONAME}")
-    IF(WIN32)
+    IF(MSVC)
         SET_TARGET_PROPERTIES(hiredis_ssl_static
             PROPERTIES COMPILE_FLAGS /Z7)
     ENDIF()