don't remap internal-use syscall macros to nonexistent time32 syscalls

riscv32 and future architectures lack the _time32 variants entirely,
so don't try to use their numbers. instead, reflect that they're not
present.

src/internal/syscall.h

@@ -201,43 +201,43 @@ static inline long __alt_socketcall(int sys, int sock, int cp, long a, long b, l
 #define SYS_sendfile SYS_sendfile64
 #endif
 
-#ifndef SYS_timer_settime
+#ifdef SYS_timer_settime32
 #define SYS_timer_settime SYS_timer_settime32
 #endif
 
-#ifndef SYS_timer_gettime
+#ifdef SYS_timer_gettime32
 #define SYS_timer_gettime SYS_timer_gettime32
 #endif
 
-#ifndef SYS_timerfd_settime
+#ifdef SYS_timerfd_settime32
 #define SYS_timerfd_settime SYS_timerfd_settime32
 #endif
 
-#ifndef SYS_timerfd_gettime
+#ifdef SYS_timerfd_gettime32
 #define SYS_timerfd_gettime SYS_timerfd_gettime32
 #endif
 
-#ifndef SYS_clock_settime
+#ifdef SYS_clock_settime32
 #define SYS_clock_settime SYS_clock_settime32
 #endif
 
-#ifndef SYS_clock_gettime
+#ifdef SYS_clock_gettime32
 #define SYS_clock_gettime SYS_clock_gettime32
 #endif
 
-#ifndef SYS_clock_getres
+#ifdef SYS_clock_getres_time32
 #define SYS_clock_getres SYS_clock_getres_time32
 #endif
 
-#ifndef SYS_clock_nanosleep
+#ifdef SYS_clock_nanosleep_time32
 #define SYS_clock_nanosleep SYS_clock_nanosleep_time32
 #endif
 
-#ifndef SYS_gettimeofday
+#ifdef SYS_gettimeofday_time32
 #define SYS_gettimeofday SYS_gettimeofday_time32
 #endif
 
-#ifndef SYS_settimeofday
+#ifdef SYS_settimeofday_time32
 #define SYS_settimeofday SYS_settimeofday_time32
 #endif