Fix linker complains about missing libraries

Fix linker complains about missing libraries

After an upgrade, I got errors like this:
  /usr/bin/ld: fwp-timing.o: undefined reference to symbol 'clock_nanosleep@@GLIBC_2.2.5'
  /usr/bin/ld: note: 'clock_nanosleep@@GLIBC_2.2.5' is defined in DSO /lib64/librt.so.1 so try adding it to the linker command line
  /lib64/librt.so.1: could not read symbols: Invalid operation

It was sufficient to fix them by adding mentioned libraries explicitely in
Makefile.omk.