cmake: move definition of Win32 flags together

This makes splitting up the library build instructions later on more
obvious and easier to achieve.

CMakeLists.txt

@@ -76,10 +76,6 @@ IF(MSVC)
 	# If you want to embed a copy of libssh2 into libgit2, pass a
 	# path to libssh2
 	OPTION( EMBED_SSH_PATH		"Path to libssh2 to embed (Windows)" OFF )
-
-	ADD_DEFINITIONS(-D_SCL_SECURE_NO_WARNINGS)
-	ADD_DEFINITIONS(-D_CRT_SECURE_NO_DEPRECATE)
-	ADD_DEFINITIONS(-D_CRT_NONSTDC_NO_DEPRECATE)
 ENDIF()
 
 
@@ -402,6 +398,9 @@ ENDIF()
 
 # Platform specific compilation flags
 IF (MSVC)
+	ADD_DEFINITIONS(-D_SCL_SECURE_NO_WARNINGS)
+	ADD_DEFINITIONS(-D_CRT_SECURE_NO_DEPRECATE)
+	ADD_DEFINITIONS(-D_CRT_NONSTDC_NO_DEPRECATE)
 
 	STRING(REPLACE "/Zm1000" " " CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")