Fix: egrep is obsolescent, use grep -E

See e.g., egrep(1) [https://linux.die.net/man/1/egrep]:

> two variant programs egrep and fgrep are available. egrep is the same
> as grep -E. fgrep is the same as grep -F. Direct invocation as either
> egrep or fgrep is deprecated

See also the rationale of the POSIX description of grep
(https://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html):

> This grep has been enhanced in an upwards-compatible way to provide
> the exact functionality of the historical egrep and fgrep commands as
> well. It was the clear intention of the standard developers to
> consolidate the three greps into a single command.

Closes: #839

openair1/PHY/TOOLS/Makefile

@@ -13,7 +13,7 @@ oai_dfts_sse4.s: oai_dfts.c
 
 
 dft_cycles_avx2: oai_dfts_avx2
-	./oai_dfts_avx2 | egrep cycles
+	./oai_dfts_avx2 | grep -E cycles
 
 oai_dfts_aarch64: oai_dfts_neon.c
 	 gcc -O2 -std=gnu99 -gdwarf-2 -lgcc -lrt -g -ggdb -o oai_dfts_neon oai_dfts_neon.c ../../../common/utils/time_meas.c ../../SIMULATION/TOOLS/taus.c $$OPENAIR_HOME/common/utils/LOG/log.c  ../../SIMULATION/TOOLS/rangen_double.c -I$$OPENAIR_HOME -I$$OPENAIR1_DIR -I$$OPENAIR_TARGETS -I$$OPENAIR_TARGETS/COMMON -I$$OPENAIR_HOME/radio/COMMON -I$$OPENAIR2_DIR -I$$OPENAIR2_DIR/COMMON -I$$OPENAIR_HOME/common/utils -I$$OPENAIR_HOME/common/utils/T -I$$OPENAIR_HOME/common/utils/msc -I$$OPENAIR_HOME/nfapi/open-nFAPI/nfapi/public_inc -DMR_MAIN -DNB_ANTENNAS_RX=1 -DNB_ANTENNAS_TX=1 -DMAX_NUM_CCs=1 -lm -lpthread