Fix crash when the user specify an march and Make the arm fix work in that case.

theano/gof/cmodule.py

@@ -1714,7 +1714,7 @@ class GCC_compiler(object):
         # or 64 bit and compile accordingly. This step is ignored for ARM
         # architectures in order to make Theano compatible with the Raspberry
         # Pi.
-        if any([not 'arm' in flag for flag in GCC_compiler.march_flags]):
+        if any([not 'arm' in flag for flag in cxxflags]):
             n_bits = local_bitwidth()
             cxxflags.append('-m%d' % n_bits)
             _logger.debug("Compiling for %s bit architecture", n_bits)