Merge branch 'maint-1.7.7' into maint

* maint-1.7.7:
  am: don't persist keepcr flag
  mingw: give waitpid the correct signature
  git symbolic-ref: documentation fix

compat/mingw.h

@@ -120,7 +120,7 @@ static inline int mingw_mkdir(const char *path, int mode)
 #define mkdir mingw_mkdir
 
 #define WNOHANG 1
-pid_t waitpid(pid_t pid, int *status, unsigned options);
+pid_t waitpid(pid_t pid, int *status, int options);
 
 #define kill mingw_kill
 int mingw_kill(pid_t pid, int sig);