sys/abi_types.h: time32_t is 64-bit on non-x86 architectures

As long as 'sys/compat/freebsd32/freebsd32.h' is used unconditionally on
all platforms (in 'kern_umtx.c' at least), the rule of thumb is to
ensure that 'struct foo32' on a 32-bit arch is type-compatible with
'struct foo' on the same arch.  In practice, this is very simple to
achieve: All 'foo32' types should be compatible with 'foo' on 32-bit
architectures, which is what we are supposed to do already for compat'
structures by design.  The recently introduced 'freebsd32_uint64_t' type
typically supports that.

This change fixes commit 87632ddf67 ("openzfs sys/types32.h: use
abi_compat.h for time32_t") which was defining 'time32_t' to 'in32_t'
for all 32-bit architectures, which is wrong but on i386.  By luck, this
did not change the size of whole 'struct ffclock_estimate32' (whose size
is compile-time asserted) because 'struct bintime32''s one would stay
the same, as even if its field 'sec' was incorrectly sized after that
commit, the 'frac' one is 64-bit and 64-bit aligned on all non-x86
architectures so its offset in 'struct bintime32' would stay the same.

Reviewed by:    kib
Fixes:          87632ddf67 ("openzfs sys/types32.h: use abi_compat.h for time32_t")
Sponsored by:   The FreeBSD Foundation
Differential Revision:  https://reviews.freebsd.org/D55283

sys/sys/abi_types.h

@@ -25,15 +25,11 @@ typedef struct {
 #endif
 } freebsd32_uint64_t;
 
-#if __SIZEOF_LONG__ == 8
-#if defined __amd64__
+#if defined(__amd64__) || defined(__i386__)
 typedef	__int32_t	time32_t;
 #else
 typedef	__int64_t	time32_t;
 #endif
-#else
-typedef	__int32_t	time32_t;
-#endif
 #define	__HAVE_TIME32_T
 
 #endif