Fix incorrect use of flags in re.sub()

The 4th argument of re.sub() is maximum number of substitutions, not
flags.

re.M affects only semantics of ^ and $, so it wouldn't have any effect
on this regexp.

tests/run/extstarargs.pyx

@@ -90,7 +90,7 @@ __doc__ = u"""
 
 import sys, re
 if sys.version_info >= (2,6):
-    __doc__ = re.sub(u"(ELLIPSIS[^>]*Error: )[^\n]*\n", u"\\1...\n", __doc__, re.M)
+    __doc__ = re.sub(u"(ELLIPSIS[^>]*Error: )[^\n]*\n", u"\\1...\n", __doc__)
 
 cdef sorteditems(d):
     l = list(d.items())