Enabled POSIX.1-2001 for use of `struct timespec' and `nanosleep'
Enabled POSIX.1-2001 for use of `struct timespec' and `nanosleep'

lib/utils_c.c cannot be compiled with option `-std=c99' because
`struct timespec' and `nanosleep' are NOT supported by ISO C99.
For use of them, POSIX.1-2001 was enabled by defining
`_POSIX_C_SOURCE' macro.

kkirstein/lacaml,rleonid/lacaml,rleonid/lacaml,kkirstein/lacaml