how use function "clock_gettime"

[alexa1970]

I install Mint13 MAYA
When I want use function "clock_gettime" I receive link error
I think problem that I have _POSIX_VERSION=200809 but in USR/INCLUDE/time.h
we have check #IF DEF __USE_POSIX199309 for function "clock_gettime"
I don't know how change directories C(I use compiler gcc) that I can use function
"clock_gettime"