semihosting: add O_BINARY flag in host_open for NT compatibility

Windows open(2) implementation opens files in text mode by default and
needs a Windows-only O_BINARY flag to open files as binary. QEMU already
knows about that flag in osdep and it is defined to 0 on non-Windows,
so we can just add it to the host_flags for better compatibility.

Signed-off-by: Evgeny Iakovlev <eiakovlev@linux.microsoft.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20230106102018.20520-1-eiakovlev@linux.microsoft.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230124180127.1881110-25-alex.bennee@linaro.org>

semihosting/syscalls.c

@@ -253,7 +253,7 @@ static void host_open(CPUState *cs, gdb_syscall_complete_cb complete,
 {
     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
     char *p;
-    int ret, host_flags;
+    int ret, host_flags = O_BINARY;
 
     ret = validate_lock_user_string(&p, cs, fname, fname_len);
     if (ret < 0) {
@@ -262,11 +262,11 @@ static void host_open(CPUState *cs, gdb_syscall_complete_cb complete,
     }
 
     if (gdb_flags & GDB_O_WRONLY) {
-        host_flags = O_WRONLY;
+        host_flags |= O_WRONLY;
     } else if (gdb_flags & GDB_O_RDWR) {
-        host_flags = O_RDWR;
+        host_flags |= O_RDWR;
     } else {
-        host_flags = O_RDONLY;
+        host_flags |= O_RDONLY;
     }
     if (gdb_flags & GDB_O_CREAT) {
         host_flags |= O_CREAT;