Don't claim to fully implement C99 in the STANDARDS section and then disclaim

compliance in the BUGS section immediately below.

lib/libc/stdio/printf.3

@@ -769,7 +769,9 @@ Always use the proper secure idiom:
 (See
 .Pa "/usr/share/doc/{to be determined}" . )
 .Sh STANDARDS
-The
+Subject to the caveats noted in the
+.Sx BUGS
+section below, the
 .Fn fprintf ,
 .Fn printf ,
 .Fn sprintf ,
@@ -782,7 +784,7 @@ conform to
 .St -ansiC
 and
 .St -isoC-99 .
-The
+With the same reservation, the
 .Fn snprintf
 and
 .Fn vsnprintf