turn off O3 compilation

Author: Doru Rathgeber

pyop2/compilation.py

@@ -238,7 +238,7 @@ def __init__(self, cppargs=[], ldargs=[], cpp=False):
         # gcc.gnu.org/bugzilla/show_bug.cgi?id=61068
         # This is the default in Ubuntu 14.04 so work around this
         # problem by turning ivopts off.
-        opt_flags = ['-march=native', '-O3', '-fno-ivopts']
+        opt_flags = ['-O0']
         if configuration['debug']:
             opt_flags = ['-O0', '-g']
         cc = "mpicc"