Fix a warning in libqi when compiling for android.
Fix a warning in libqi when compiling for android.

wchar_t is unsigned int on android and c >= 0 is no op (always true).
Analysing the code with Philippe and Joel, we ended up thinking that this code does not have sense and should be equal to proposed fix. Tests are passing.

Change-Id: I25426a1cafddde2cc827f04e13cf4168536a5be8
Reviewed-on: http://gerrit.aldebaran.lan/66872
Reviewed-by: jlamotte <70353e7b0c7d18b7fc75605daf0ccba69fcd3222@aldebaran.com>
Tested-by: icesi <89c787ac7bf5392f554c766f7de8c2903214fbf8@aldebaran.com>

aldebaran/libqi,aldebaran/libqi,aldebaran/libqi