http: adjust test threshold for larger suse buffers
http: adjust test threshold for larger suse buffers

My theory is that suse has larger TCP buffer sizes
by default.  I now check over 100MB, rather than over 2MB.
100MB is ~halfway between the 1MB limit and the 200MB
request that's attempted.

R=golang-dev, dsymonds
CC=golang-dev
http://codereview.appspot.com/4926048

tv42/old-go,gnanderson/go,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,dsriram/golang,dsriram/golang,apparentlymart/golang,tv42/old-go,gnanderson/go,apparentlymart/golang,tv42/old-go,dsriram/golang,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,dsriram/golang,dsriram/golang,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,apparentlymart/golang,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,dsriram/golang,dsriram/golang,gnanderson/go,tv42/old-go