mingw.h: add dummy functions for sigset_t operations

Windows does not have POSIX-like signals, and so we ignore all
operations on the non-existent signal mask machinery.

Do not turn sigemptyset into a function, but leave it a macro that
erases the code in the argument because it is used to set sa_mask
of a struct sigaction, but our dummy in mingw.h does not have that
member.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/mingw.h

@@ -69,7 +69,6 @@ struct sigaction {
 	sig_handler_t sa_handler;
 	unsigned sa_flags;
 };
-#define sigemptyset(x) (void)0
 #define SA_RESTART 0
 
 struct itimerval {
@@ -116,6 +115,12 @@ static inline int fcntl(int fd, int cmd, ...)
 }
 /* bash cannot reliably detect negative return codes as failure */
 #define exit(code) exit((code) & 0xff)
+#define sigemptyset(x) (void)0
+static inline int sigaddset(sigset_t *set, int signum)
+{ return 0; }
+#define SIG_UNBLOCK 0
+static inline int sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
+{ return 0; }
 
 /*
  * simple adaptors

t/t0005-signals.sh

@@ -39,12 +39,12 @@ test_expect_success 'create blob' '
 	git add file
 '
 
-test_expect_success 'a constipated git dies with SIGPIPE' '
+test_expect_success !MINGW 'a constipated git dies with SIGPIPE' '
 	OUT=$( ((large_git; echo $? 1>&3) | :) 3>&1 )
 	test "$OUT" -eq 141
 '
 
-test_expect_success 'a constipated git dies with SIGPIPE even if parent ignores it' '
+test_expect_success !MINGW 'a constipated git dies with SIGPIPE even if parent ignores it' '
 	OUT=$( ((trap "" PIPE; large_git; echo $? 1>&3) | :) 3>&1 )
 	test "$OUT" -eq 141
 '