fix Empty console Output on R under processing. refs #7643

This commit will fix the problem of empty console output on R under processing.

- This problem seems to occur in windows 32bit only.
- I think that a fundamental cause is probably the handling of new line code of python 2.7.4. 
 - QGIS on windows 64bit depends on python 2.7.5 doesn't occur this problem.
- In the original code, the carriage return remains when line feed are removed. So the part of compare string will always be in false.