Add make bench for building the benchmarks

Author: ViralBShah

test/Makefile

@@ -3,6 +3,8 @@ include ../Make.inc
 
 all: test-double test-float # test-double-system test-float-system
 
+bench: bench-syslibm bench-openlibm
+
 test-double: test-double.c libm-test.c
 	$(CC) $(CFLAGS) -g $@.c -D__BSD_VISIBLE -I ../include -I../src ../libopenlibm.a -o $@
 
@@ -14,3 +16,12 @@ test-double-system: test-double.c libm-test.c
 
 test-float-system: test-float.c libm-test.c
 	$(CC) $(CFLAGS) -g $< -DSYS_MATH_H -lm -o $@
+
+bench-openlibm: libm-bench.cpp
+	$(CC) $(CFLAGS) -O2 $< ../libopenlibm.a -o $@
+
+bench-syslibm: libm-bench.cpp
+	$(CC) $(CFLAGS) -O2 $< -lm -o $@
+
+clean:
+	rm -fr test-double test-float test-double-system test-float-system bench-openlibm bench-syslibm *.dSYM