Add missing include directives.

These are required for std::accumulate (numeric) and
std::abs (cmath).

src/opm/test_util/EclFilesComparator.cpp

@@ -23,6 +23,8 @@
 #include <algorithm>
 #include <ert/ecl/ecl_file.h>
 #include <ert/ecl/ecl_grid.h>
+#include <cmath>
+#include <numeric>
 
 bool ECLFilesComparator::keywordValidForComparing(const std::string& keyword) const {
     auto it = std::find(keywords1.begin(), keywords1.end(), keyword);

src/opm/test_util/summaryComparator.cpp

@@ -22,6 +22,8 @@
 #include <ert/util/int_vector.h>
 #include <ert/util/bool_vector.h>
 #include <opm/common/ErrorMacros.hpp>
+#include <cmath>
+#include <numeric>
 
 SummaryComparator::SummaryComparator(const char* basename1, const char* basename2, double absoluteTolerance, double relativeTolerance){
     ecl_sum1 = ecl_sum_fread_alloc_case(basename1, ":");