Removed bogus includes of <sys/types.h> from synopses.

This commit covers the man pages for most of the ANSI library functions.
A few others such as strtol.3 have to mention <sys/types.h> because they
mix ANSI interfaces with less well designed extensions.

lib/libc/gen/clock.3

@@ -42,7 +42,7 @@
 .Nm clock
 .Nd determine processor time used
 .Sh SYNOPSIS
-.Fd #include <sys/types.h>
+.Fd #include <time.h>
 .Ft clock_t
 .Fn clock void
 .Sh DESCRIPTION

lib/libc/gen/time.3

@@ -42,7 +42,6 @@
 .Nm time
 .Nd get time of day
 .Sh SYNOPSIS
-.Fd #include <sys/types.h>
 .Fd #include <time.h>
 .Ft time_t
 .Fn time "time_t *tloc"

lib/libc/stdtime/ctime.3

@@ -46,7 +46,6 @@
 .Nd transform binary date and time value to
 .Tn ASCII
 .Sh SYNOPSIS
-.Fd #include <sys/types.h>
 .Fd #include <time.h>
 .Vt extern char *tzname[2];
 .Ft char *

lib/libc/stdtime/strftime.3

@@ -42,9 +42,7 @@
 .Nm strftime
 .Nd format date and time
 .Sh SYNOPSIS
-.Fd #include <sys/types.h>
 .Fd #include <time.h>
-.Fd #include <string.h>
 .Ft size_t
 .Fn strftime "char *buf" "size_t maxsize" "const char *format" "const struct tm *timeptr"
 .Sh DESCRIPTION

lib/libc/stdtime/time2posix.3

@@ -3,7 +3,6 @@
 time2posix, posix2time \- convert seconds since the Epoch
 .SH SYNOPSIS
 .nf
-.B #include <sys/types.h>
 .B #include <time.h>
 .PP
 .B time_t time2posix(t)