Add benchmarks for unsupported modules and extend supported benchmarks

libeigen/eigen!2179

Closes #3036

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

benchmarks/Eigenvalues/bench_eigensolver.cpp

@@ -5,7 +5,11 @@
 
 using namespace Eigen;
 
-typedef float Scalar;
+#ifndef SCALAR
+#define SCALAR float
+#endif
+
+typedef SCALAR Scalar;
 
 static void BM_SelfAdjointEigenSolver(benchmark::State& state) {
   int n = state.range(0);