add -lrt

Makefile

@@ -35,7 +35,7 @@ PARAMS_SSE = $(call cpufeature,sse,-msse) $(call cpufeature,sse2,-msse2) $(call
 PARAMS_NEON = -fshort-double -mfloat-abi=hard -march=armv7-a -mtune=cortex-a8 -mfpu=neon -mvectorize-with-neon-quad -funsafe-math-optimizations -Wformat=0
 PARAMS_SIMD = $(if $(call cpufeature,sse,dummy-text),$(PARAMS_SSE),$(PARAMS_NEON))
 PARAMS_LOOPVECT = -O3 -ffast-math -fdump-tree-vect-details -dumpbase dumpvect
-PARAMS_LIBS = -g -lm -lfftw3f -DUSE_FFTW -DLIBCSDR_GPL
+PARAMS_LIBS = -g -lm -lrt -lfftw3f -DUSE_FFTW -DLIBCSDR_GPL
 PARAMS_SO = -fpic  
 PARAMS_MISC = -Wno-unused-result