Removed all instances of XXX in preparation for relaxing of FIXME rule

src/test/bench/shootout-fasta-redux.rs

@@ -56,7 +56,7 @@ static HOMO_SAPIENS: [AminoAcid, ..4] = [
     AminoAcid { c: 't' as u8, p: 0.3015094502008 },
 ];
 
-// XXX: Use map().
+// FIXME: Use map().
 fn sum_and_scale(a: &'static [AminoAcid]) -> ~[AminoAcid] {
     let mut result = ~[];
     let mut p = 0f32;

src/test/bench/shootout-k-nucleotide.rs

@@ -49,7 +49,7 @@ impl Code {
         code
     }
 
-    // XXX: Inefficient.
+    // FIXME: Inefficient.
     fn unpack(&self, frame: i32) -> ~str {
         let mut key = **self;
         let mut result = ~[];