Add bench k-nucleotide as per

http://benchmarksgame.alioth.debian.org/u64q/knucleotide.html

bench/nucleotide/Makefile

@@ -0,0 +1,22 @@
+CC=cc -std=c11
+CXX=c++ -std=c++11
+CFLAGS=-O2 -march=native -Wall
+CPPFLAGS=-I../..
+
+all: k-nucleotide
+
+k-nucleotide: k-nucleotide.exe data.txt
+	time ./k-nucleotide.exe < data.txt
+
+k-nucleotide.exe: nucleotide.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) nucleotide.c -o k-nucleotide.exe -lpthread
+
+data.txt: fasta.exe
+	./fasta.exe 25000000 > data.txt
+
+fasta.exe: fasta.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -fopenmp fasta.c -o fasta.exe
+
+clean:
+	rm -f *.exe *~ *.o data.txt
+