Failures on travis and winnie cmake

[robe]

I started to get this failure on both travis and winnie and on my local gcc81

[35m[1mScanning dependencies of target check[0m
Test project E:/jenkins/geos/branches/build64cmake
    Start 1: test_geos_unit
1/8 Test #1: test_geos_unit ...................***Failed    1.12 sec
    Start 2: test_xmltester
2/8 Test #2: test_xmltester ...................   Passed   29.65 sec
    Start 3: test_bug234
3/8 Test #3: test_bug234 ......................   Passed    0.04 sec
    Start 4: test_sweep_line_speed
4/8 Test #4: test_sweep_line_speed ............   Passed    5.69 sec
    Start 5: perf_class_sizes
5/8 Test #5: perf_class_sizes .................   Passed    0.02 sec
    Start 6: perf_iterated_buffer
6/8 Test #6: perf_iterated_buffer .............   Passed   31.37 sec
    Start 7: perf_rectangle_intersects
7/8 Test #7: perf_rectangle_intersects ........   Passed    1.49 sec
    Start 8: perf_memleak_mp_prep
8/8 Test #8: perf_memleak_mp_prep .............   Passed   24.28 sec

88% tests passed, 1 tests failed out of 8

Total Test time (real) =  93.71 sec

The following tests FAILED:
	  1 - test_geos_unit (Failed)
Errors while running CTest

I thought it might be related to #914, but as I recall when I was testing cvvergara's branch I didn't get an error. GEOS 3.7.0rc1 is fine, so must have been something committed after that.

or perhaps its a combination of the the #914 fix and an earlier patch, like possibly - ​https://github.com/libgeos/geos/pull/102