VS 2017.4 Preview Test failures

[garyfurnish]

With commit bfcbfe3c58064cd1ffabbce49a95c6c20351c96e (HEAD, origin/master) and VS 2017.4 Preview:

236467-testing.capture-output bin.v2\libs\accumulators\test\p_square_cumul_dist.test\msvc-14.1\debug\address-model-64\iterator_debugging-off\link-static\threading-multi\p_square_cumul_dist.run
236468-====== BEGIN OUTPUT ======
236469-Running 1 test case...
236470-libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0331329} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.010331329148570989} and histogram[i].second{0.01} exceeds 3%
236471-libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0372556} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.020755484496021825} and histogram[i].second{0.02001} exceeds 3%
236472-libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0326898} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.030980693519017} and histogram[i].second{0.029999999999999999} exceeds 3%
236473-libs/accumulators/test/p_square_cumul_dist.cpp(66): error: in "p_square_cumulative_distribution test/test_stat": difference{0.0306804} between 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )){0.041227215128245343} and histogram[i].second{0.040000000000000001} exceeds 3%
236474-
236475:*** 4 failures are detected in the test module "Master Test Suite"
236476- 
236477-EXIT STATUS: 201 
236478-====== END OUTPUT ======

237337-testing.capture-output bin.v2\libs\accumulators\test\weighted_median.test\msvc-14.1\debug\address-model-64\iterator_debugging-off\link-static\threading-multi\weighted_median.run
237338-====== BEGIN OUTPUT ======
237339-Running 1 test case...
237340-libs/accumulators/test/weighted_median.cpp(50): error: in "weighted_median test/test_stat": difference{0.0327894} between 1.{1} and weighted_median(acc_dens){0.96825159071079681} exceeds 3%
237341-libs/accumulators/test/weighted_median.cpp(51): error: in "weighted_median test/test_stat": difference{0.0316788} between 1.{1} and weighted_median(acc_cdist){0.96929395242297978} exceeds 3%
237342-
237343:*** 2 failures are detected in the test module "Master Test Suite"
237344- 
237345-EXIT STATUS: 201 
237346-====== END OUTPUT ======

[kuhlenough]

We've seen this one with clang v6.0 with VxWorks. The common element with VS would be the Dinkum STL