bsd-user: define TARGET_RFSPAWN for rfork to use vfork(2) semantics, …

…and fix RLIM_INFINITY

RLIM_INFINITY on FreeBSD, OpenBSD and NetBSD has value of ~(1<<63), caculated
one way or another.

Signed-off-by: Kyle Evans <kevans@FreeBSD.org>
Signed-off-by: Karim Taha <kariem.taha2.7@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20230925182425.3163-2-kariem.taha2.7@gmail.com>

bsd-user/syscall_defs.h

@@ -130,11 +130,7 @@ struct target_freebsd_timeval {
 /*
  *  sys/resource.h
  */
-#if defined(__FreeBSD__)
 #define TARGET_RLIM_INFINITY    RLIM_INFINITY
-#else
-#define TARGET_RLIM_INFINITY    ((abi_ulong)-1)
-#endif
 
 #define TARGET_RLIMIT_CPU       0
 #define TARGET_RLIMIT_FSIZE     1
@@ -390,6 +386,10 @@ struct target_freebsd_flock {
     int32_t l_sysid;
 } QEMU_PACKED;
 
+/* sys/unistd.h */
+/* user: vfork(2) semantics, clear signals */
+#define TARGET_RFSPAWN (1U << 31)
+
 #define safe_syscall0(type, name) \
 type safe_##name(void) \
 { \