Also test for target.

CMakeLists.txt

@@ -254,7 +254,7 @@ else()
   set(OPENCV_DOC_INSTALL_PATH share/OpenCV/doc)
 endif()
 
-if(CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
+if(WIN32 AND CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
   if(DEFINED OpenCV_RUNTIME AND DEFINED OpenCV_ARCH)
     set(OpenCV_INSTALL_BINARIES_PREFIX "${OpenCV_ARCH}/${OpenCV_RUNTIME}/")
   else()
@@ -294,7 +294,7 @@ if(ANDROID)
 else()
   set(LIBRARY_OUTPUT_PATH         "${OpenCV_BINARY_DIR}/lib")
   set(3P_LIBRARY_OUTPUT_PATH      "${OpenCV_BINARY_DIR}/3rdparty/lib${LIB_SUFFIX}")
-  if(CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
+  if(WIN32 AND CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
     if(OpenCV_STATIC)
       set(OPENCV_LIB_INSTALL_PATH   "${OpenCV_INSTALL_BINARIES_PREFIX}staticlib${LIB_SUFFIX}")
     else()