[ex] add example C file

Author: lotabout

hello.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+int fibonacci(int i) {
+    if (i <= 1) {
+        return 1;
+    }
+    return fibonacci(i-1) + fibonacci(i-2);
+}
+
+int main()
+{
+    int i;
+    i = 0;
+    while (i <= 10) {
+        printf("fibonacci(%2d) = %d\n", i, fibonacci(i));
+        i = i + 1;
+    }
+    return 0;
+}