Consider use `BenchmarkTools.jl` when benchmarking Julia code about blogposts

[Moelf]

btw, you also need this diff for the C implementation for it to be fair (use 64 bit integers)

diff --git a/r_python_julia/linear_search.c b/r_python_julia/linear_search.c
index 2a5f373..f036f48 100644
--- a/r_python_julia/linear_search.c
+++ b/r_python_julia/linear_search.c
@@ -16,7 +16,7 @@
 #define ARRAY_SIZE 1000000

 // 0.26 seconds
-int for_search(const int *vec, int size, int x) {
+int for_search(const int64_t *vec, int size, int x) {
   for (int i=0;i<size;i++)
     if (vec[i] == x)
       return 1;
@@ -27,7 +27,7 @@ int main() {
   char *filename = "vec.txt";
   FILE *f;
   char line[MAX_LINE_LEN];
-  int vec[ARRAY_SIZE];
+  int64_t vec[ARRAY_SIZE];
   clock_t start, end;
   double elapsed_used;

@@ -35,7 +35,7 @@ int main() {
   f = fopen(filename, "r");
   int i = 0;
   while (fgets(line, MAX_LINE_LEN, f) != NULL)
-    vec[i++] = (int) strtoul(line, NULL, 0);
+    vec[i++] = (int64_t) strtoul(line, NULL, 0);
   fclose(f);
   printf("%d records\n", i);