Specify Windows 7+ API target in CMake config

MinGW targets an older version of Windows by default, and wouldn't pull the necessary declarations from the headers without this option

PiperOrigin-RevId: 306200672
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 837d76d..c888243 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1594,6 +1594,10 @@
 
 TARGET_INCLUDE_DIRECTORIES(XNNPACK PUBLIC include)
 TARGET_INCLUDE_DIRECTORIES(XNNPACK PRIVATE src)
+IF(WIN32)
+  # Target Windows 7+ API
+  TARGET_COMPILE_DEFINITIONS(XNNPACK PRIVATE _WIN32_WINNT=0x0601)
+ENDIF()
 SET_TARGET_PROPERTIES(XNNPACK PROPERTIES PUBLIC_HEADER include/xnnpack.h)
 
 # ---[ Find libm