test: tweak bug273.go to not have constant len < cap when calling make
test: tweak bug273.go to not have constant len < cap when calling make

The current spec says that when calling make, if both len and
cap are constant, it is an error if len > cap.  The gc
compiler does not yet implement that, but when it does this
will need to change.  Changing it now for the benefit of
gccgo.

R=gri
CC=golang-dev
https://codereview.appspot.com/6867064

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