Update to sagemath 6.8

sagemath-cbc.patch

@@ -1,12 +1,14 @@
-diff -up src/module_list.py.orig src/module_list.py
---- src/module_list.py.orig	2015-04-03 15:09:20.200406141 -0300
-+++ src/module_list.py	2015-04-03 15:09:39.744406890 -0300
-@@ -2187,7 +2187,7 @@ if (os.path.isfile(SAGE_INC + "/cplex.h"
-                   libraries = ["stdc++", "cplex"])
-         )
+diff -up src/sage/numerical/backends/coin_backend.pyx.orig src/sage/numerical/backends/coin_backend.pyx
+--- src/sage/numerical/backends/coin_backend.pyx.orig	2015-11-06 10:36:17.498631801 -0200
++++ src/sage/numerical/backends/coin_backend.pyx	2015-11-06 10:36:40.210632670 -0200
+@@ -761,8 +761,8 @@ cdef class CoinBackend(GenericBackend):
+         model.setLogLevel(old_logLevel)
+ 
+         # multithreading
+-        import multiprocessing
+-        model.setNumberThreads(multiprocessing.cpu_count())
++        #import multiprocessing
++        #model.setNumberThreads(multiprocessing.cpu_count())
+ 
+         model.branchAndBound()
  
--if is_package_installed('cbc'):
-+if 1:
-     ext_modules.append(
-         Extension("sage.numerical.backends.coin_backend",
-                   ["sage/numerical/backends/coin_backend.pyx"],