devel/llvm33: failed to compile due to CLOCK_PROCESS_CPUTIME_ID issue

[O. Hartmann]

On a laptop, running FreeBSD 9.2-PRERELEASE #0 r255170: Tue Sep  3
11:54:29 CEST 2013 amd64, compiling/updating port devel/llvm33 fails
with the error shown below.

The port is at llvm-3.3_2 and is supposed to be updated to 
llvm-3.3_4.

On FreeBSD 10.0-CURRENT there is no problem compiling the port.

[...]
llvm[1]: Compiling Signals.cpp for Release build
In file included from Process.cpp:85:
/usr/ports/devel/llvm33/work/llvm-3.3.src/lib/Support/Unix/Process.inc:75:23:
error: use of undeclared identifier 'CLOCK_PROCESS_CPUTIME_ID' if
(::clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &TS) == 0) ^
1 error generated.
gmake[1]: ***
[/usr/ports/devel/llvm33/work/llvm-3.3.src/lib/Support/Release/Process.o]
Error 1 gmake[1]: *** Waiting for unfinished jobs.... gmake[1]: Leaving
directory `/usr/ports/devel/llvm33/work/llvm-3.3.src/lib/Support'
gmake: *** [all] Error 1