More strict syntax for test/gigs/5110.gie.failing (LAEA)

[rouault]

Current results are that we pass the simple one-time forward / reverse tests, but not repeated 1000 times:

$ bin/gie ../test/gigs/5110.gie.failing
-------------------------------------------------------------------------------
Reading file '../test/gigs/5110.gie.failing'
-------------------------------------------------------------------------------
proj=pipeline step init=epsg:4258 inv step init=epsg:3035
-------------------------------------------------------------------------------
     FAILURE in 5110.gie.failing(116):
     roundtrip deviation: 105.138717 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(120):
     roundtrip deviation: 168.120679 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(124):
     roundtrip deviation: 344.822744 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(128):
     roundtrip deviation: 759.297462 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(132):
     roundtrip deviation: 1311.809746 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(140):
     roundtrip deviation: 344.822713 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(144):
     roundtrip deviation: 344.822789 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(148):
     roundtrip deviation: 344.822744 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(152):
     roundtrip deviation: 344.822853 mm, expected: 6.000000 mm
     -----
     FAILURE in 5110.gie.failing(156):
     roundtrip deviation: 344.822747 mm, expected: 6.000000 mm
-------------------------------------------------------------------------------
total: 23 tests succeeded,  0 tests skipped, 10 tests FAILED!
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