fix some file extensions

Task/Fibonacci-sequence/C/fibonacci-sequence-1.c

@@ -1,3 +1,3 @@
-long long unsigned fib(unsigned n) {
-    return n < 2 ? n : fib(n - 1) + fib(n - 2);
+long long int fibb(long long int a, long long int b, int n) {
+return (--n>0)?(fibb(b, a+b, n)):(a);
 }

Task/Fibonacci-sequence/C/fibonacci-sequence-2.c

@@ -1,10 +1,9 @@
-long long unsigned fib(unsigned n) {
-    long long unsigned last = 0, this = 1, new, i;
-    if (n < 2) return n;
-    for (i = 1 ; i < n ; ++i) {
-        new = last + this;
-        last = this;
-        this = new;
-    }
-    return this;
+long long int fibb(int n) {
+	int fnow = 0, fnext = 1, tempf;
+	while(--n>0){
+		tempf = fnow + fnext;
+		fnow = fnext;
+		fnext = tempf;
+		}
+		return fnow;	
 }