Revert "Merge 'mingw-isatty' into HEAD"

Prepare to merge the latest iteration of the mingw-isatty patch series.

This reverts commit 4af28e2fb4, reversing
changes made to 6cd98a7c65.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

compat/mingw.h

@@ -472,9 +472,6 @@ int mingw_raise(int sig);
  * ANSI emulation wrappers
  */
 
-int winansi_isatty(int fd);
-#define isatty winansi_isatty
-
 void winansi_init(void);
 HANDLE winansi_get_osfhandle(int fd);
 

compat/winansi.c

@@ -24,9 +24,6 @@ static void set_interactive(int fd, int bit)
 
 #endif
 
-/* In this file, we actually want to use Windows' own isatty(). */
-#undef isatty
-
 /*
  ANSI codes used by git: m, K
 
@@ -663,36 +660,6 @@ static void detect_msys_tty(int fd)
 
 #endif
 
-int winansi_isatty(int fd)
-{
-	int res = isatty(fd);
-
-	if (res) {
-		/*
-		 * Make sure that /dev/null is not fooling Git into believing
-		 * that we are connected to a terminal, as "_isatty() returns a
-		 * nonzero value if the descriptor is associated with a
-		 * character device."; for more information, see
-		 *
-		 * https://msdn.microsoft.com/en-us/library/f4s0ddew.aspx
-		 */
-		HANDLE handle = (HANDLE)_get_osfhandle(fd);
-		if (fd == STDIN_FILENO) {
-			DWORD dummy;
-
-			if (!GetConsoleMode(handle, &dummy))
-				res = 0;
-		} else if (fd == STDOUT_FILENO || fd == STDERR_FILENO) {
-			CONSOLE_SCREEN_BUFFER_INFO dummy;
-
-			if (!GetConsoleScreenBufferInfo(handle, &dummy))
-				res = 0;
-		}
-	}
-
-	return res;
-}
-
 void winansi_init(void)
 {
 	int con1, con2;