ignore trailing whitespace when comparing the test output
Trac #15469: Symmetrica spkg-check fails due to whitespace

Fails to build with `SPKG_CHECK=yes` with the vexing
{{{
Successfully installed symmetrica-2.0.p9
Running the test suite for symmetrica-2.0.p9...
gcc -O2 -g  -DFAST -DALLTRUE   -c -o test.o test.c
gcc test.o -o test -L.  -lsymmetrica -lm
integerobject
4c4
<  960000.000000.000000.000000.000000
---
>  960000.000000.000000.000000.000000
Error: The Symmetrica check failed.
}}}
Closer inspection shows the difference is due to trailing whitespace.

URL: http://trac.sagemath.org/15469
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s):