Enabled pthreads backend for mingw

CMakeLists.txt

@@ -188,7 +188,7 @@ OCV_OPTION(WITH_QUICKTIME      "Use QuickTime for Video I/O insted of QTKit" OFF
 OCV_OPTION(WITH_TBB            "Include Intel TBB support"                   OFF  IF (NOT IOS AND NOT WINRT) )
 OCV_OPTION(WITH_OPENMP         "Include OpenMP support"                      OFF)
 OCV_OPTION(WITH_CSTRIPES       "Include C= support"                          OFF  IF (WIN32 AND NOT WINRT)  )
-OCV_OPTION(WITH_PTHREADS_PF    "Use pthreads-based parallel_for"             ON   IF (NOT WIN32) )
+OCV_OPTION(WITH_PTHREADS_PF    "Use pthreads-based parallel_for"             ON   IF (NOT WIN32 OR MINGW) )
 OCV_OPTION(WITH_TIFF           "Include TIFF support"                        ON   IF (NOT IOS) )
 OCV_OPTION(WITH_UNICAP         "Include Unicap support (GPL)"                OFF  IF (UNIX AND NOT APPLE AND NOT ANDROID) )
 OCV_OPTION(WITH_V4L            "Include Video 4 Linux support"               ON   IF (UNIX AND NOT ANDROID) )