log: allow color highlighting in Cygwin's mintty

Configure will detect the availability of the Windows' console functions and set
HAVE_SETCONSOLETEXTATTRIBUTE.  Meaning av_log will use those functions to
control colours.  When ffmpeg is run in Cygwin's mintty terminal emulator it
will not use colour highlighting in this case.

Mintty responds to the usual escape code colours (it even supports 256 colours).
Windows' cmd.exe does not.  Fortunately it seems that Cygwin's emulation layer
now translates the basic 16 colours into Windows' Console command functions.

That means that we can have av_log use the standard colour commands and let
ffmpeg print colours in both mintty and cmd.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/log.c

@@ -50,7 +50,7 @@ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 static int av_log_level = AV_LOG_INFO;
 static int flags;
 
-#if HAVE_SETCONSOLETEXTATTRIBUTE
+#if defined(_WIN32) && !defined(__MINGW32CE__) && HAVE_SETCONSOLETEXTATTRIBUTE
 #include <windows.h>
 static const uint8_t color[16 + AV_CLASS_CATEGORY_NB] = {
     [AV_LOG_PANIC  /8] = 12,
@@ -115,7 +115,7 @@ static int use_color = -1;
 
 static void check_color_terminal(void)
 {
-#if HAVE_SETCONSOLETEXTATTRIBUTE
+#if defined(_WIN32) && !defined(__MINGW32CE__) && HAVE_SETCONSOLETEXTATTRIBUTE
     CONSOLE_SCREEN_BUFFER_INFO con_info;
     con = GetStdHandle(STD_ERROR_HANDLE);
     use_color = (con != INVALID_HANDLE_VALUE) && !getenv("NO_COLOR") &&
@@ -146,7 +146,7 @@ static void colored_fputs(int level, int tint, const char *str)
     if (use_color < 0)
         check_color_terminal();
 
-#if HAVE_SETCONSOLETEXTATTRIBUTE
+#if defined(_WIN32) && !defined(__MINGW32CE__) && HAVE_SETCONSOLETEXTATTRIBUTE
     if (use_color && level != AV_LOG_INFO/8)
         SetConsoleTextAttribute(con, background | color[level]);
     fputs(str, stderr);