Comment cleanup v3: trailing ??, informal language, FIXME/TODO colons

libeigen/eigen!2197

Co-authored-by: Rasmus Munk Larsen <rmlarsen@gmail.com>

bench/benchmark-blocking-sizes.cpp

@@ -381,7 +381,7 @@ void try_run_some_benchmarks(vector<benchmark_t>& benchmarks, double time_start,
         // Clock speed is now higher than we previously measured.
         // Either our initial measurement was inaccurate, which won't happen
         // too many times as we are keeping the best clock speed value and
-        // and allowing some tolerance; or something really weird happened,
+        // and allowing some tolerance; or an unexpected condition occurred,
         // which invalidates all benchmark results collected so far.
         // Either way, we better restart all over again now.
         if (benchmark_index) {

bench/eig33.cpp

@@ -101,7 +101,7 @@ void eigen33(const Matrix& mat, Matrix& evecs, Vector& evals) {
   // compute the eigen vectors
   // **here we assume 3 different eigenvalues**
 
-  // "optimized version" which appears to be slower with gcc!
+  // "optimized version" which is slower with GCC!
   //     Vector base;
   //     Scalar alpha, beta;
   //     base <<   scaledMat(1,0) * scaledMat(2,1),