fix a GCC 7 warning

[andlaus]

GCC 7 warns

dynamic exception specifications are deprecated in C++11; use ‘noexcept’ instead [-Wdeprecated]

here.

on an unreleated but IMO interesting note, GCC 7 seems to become a great release for our purposes: on my machine the linearization performance improved by about 20% using flow_ebos with the norne deck when compared to GCC 5.4.0:

================    End of simulation     ===============

Total time taken (seconds):   661.888
Solver time (seconds):        658.491
 Assembly time (seconds):     284.158
 Linear solve time (seconds): 313.216
 Update time (seconds):       9.94308
 Output write time (seconds): 0.00081154
Overall Well Iterations:      890
Overall Linearizations:       1997
Overall Newton Iterations:    1653
Overall Linear Iterations:    24167

these figures need to taken with a grain of salt, though: I had to disable output because it segfaulted (this is probably related to OPM/opm-simulators#1046) and I had to recompile boost because of linker errors. the latter caused me to loose another 3 hours (or so).

[alfbr]

If that is really the case, it seems Christmas presents came early this year :-)

[andlaus]

or rather late for last year ;)

[dr-robertk]

It's more like Christmas and Easter together ;-).

[andlaus]

@atgeirr: mind pressing green here?