ec: Add -msse2 option to avoid fedora/rawhide compilation errors

This solves a compilation error on some compiler versions.
To avoid compilation issues on non-Intel architectures, patch
http://review.gluster.org/8381/ has already been merged. It
disables ec on those architectures.

These modifications are temporary patches until a proper
solution for bug #1125166 is ready.

This is a backport of http://review.gluster.org/8395/

Change-Id: I74d0b79e84601cc4f86ad08ce0f8102b99a79a68
BUG: 1125277
Signed-off-by: Xavier Hernandez <xhernandez@datalab.es>
Reviewed-on: http://review.gluster.org/8396
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>