common-main.c: fflush stdout buffer upon exit

By default, the buffer type of Windows' `stdout` is unbuffered (_IONBF),
and there is no need to manually fflush `stdout`.

But some programs, such as the Windows Filtering Platform driver
provided by the security software, may change the buffer type of
`stdout` to full buffering. This nees `fflush(stdout)` to be called
manually, otherwise there will be no output to `stdout`.

Signed-off-by: MinarKotonoha <chengzhuo5@qq.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: chengzhuo5

Diff for: common-main.c

@@ -77,6 +77,13 @@ static void check_bug_if_BUG(void)
 /* We wrap exit() to call common_exit() in git-compat-util.h */
 int common_exit(const char *file, int line, int code)
 {
+	/*
+	 *  Windows Filtering Platform driver provided by the security software
+	 * may change buffer type of stdout from _IONBF to _IOFBF.
+	 * It will no output without fflush manually.
+	 */
+	fflush(stdout);
+
 	/*
 	 * For non-POSIX systems: Take the lowest 8 bits of the "code"
 	 * to e.g. turn -1 into 255. On a POSIX system this is