benchmark: get rid of 'static inline' definition

The usage of a 'static inline' function definition in the 'bench.h'
is resulting in separate independent function definitions in each
translation unit from which the header is included. This is
increasing the size of compiled code unnecessarily.
diff --git a/include/osmocom/gapk/bench.h b/include/osmocom/gapk/bench.h
index 02c28db..1cfbeb3 100644
--- a/include/osmocom/gapk/bench.h
+++ b/include/osmocom/gapk/bench.h
@@ -24,27 +24,25 @@
 #include <osmocom/gapk/benchmark.h>
 #include <osmocom/gapk/codecs.h>
 
-static inline void benchmark_store(enum osmo_gapk_codec_type codec,
-	int encode, unsigned long cycles)
-{
-	struct osmo_gapk_bench_cycles *bc = &osmo_gapk_bench_codec[codec];
-
-	if (encode) {
-		bc->enc_used = (bc->enc_used + 1) % OSMO_GAPK_CYCLES_NUM_AVG;
-		bc->enc[bc->enc_used] = cycles;
-	} else {
-		bc->dec_used = (bc->dec_used + 1) % OSMO_GAPK_CYCLES_NUM_AVG;
-		bc->dec[bc->dec_used] = cycles;
-	}
-}	
-
 #define BENCHMARK_START					\
 	do {						\
 		cycles_t _cycles_start, _cycles_stop;	\
+		struct osmo_gapk_bench_cycles *_bc;	\
 		_cycles_start = get_cycles()
 
-#define BENCHMARK_STOP(codec, enc)			\
-		_cycles_stop = get_cycles();		\
-		benchmark_store(codec, enc,		\
-			_cycles_stop - _cycles_start);	\
+#define BENCHMARK_STOP(codec, encode)				\
+		_cycles_stop = get_cycles();			\
+		_bc = &osmo_gapk_bench_codec[codec];		\
+								\
+		if (encode) {					\
+			_bc->enc_used = (_bc->enc_used + 1)	\
+				% OSMO_GAPK_CYCLES_NUM_AVG;	\
+			_bc->enc[_bc->enc_used] =		\
+				_cycles_stop - _cycles_start;	\
+		} else {					\
+			_bc->dec_used = (_bc->dec_used + 1)	\
+				% OSMO_GAPK_CYCLES_NUM_AVG;	\
+			_bc->dec[_bc->dec_used] =		\
+				_cycles_stop - _cycles_start;	\
+		}						\
 	} while (0)