prepare dsp code to c++ migration #1317

Job	Run time
build (-Denable-profiling=1)	1m 48s
build (-Denable-floats=1 -Denable-profiling=1)	1m 40s
build (-Denable-floats=1)	59s
build (-Denable-trap-on-fpe=1)	1m 10s
build (-Denable-fpe-check=1)	1m 10s
build (-Denable-ipv6=0)	1m 12s
build (-Denable-network=0)	1m 42s
build (-Denable-aufile=0)	1m 27s
build (-DBUILD_SHARED_LIBS=0)	1m 2s
build (-Denable-ubsan=1 -Denable-debug=1)	1m 37s
build (-Denable-debug=1 -DCMAKE_C_FLAGS_DEBUG=-fuse-ld=gold)	1m 0s
build (clang-7, clang++-7)	1m 3s
build (clang-8, clang++-8)	56s
build (clang-10, clang++-10)	1m 35s
build (clang-12, clang++-12)	54s
build (clang-10, clang++-10, -DBUILD_SHARED_LIBS=0)	1m 20s
	20m 35s

Provide feedback