Config: Suppress compiler warnings for floatmath

Change-Id: I91c7fb0eeb1375d8130f1047891a5b7f90e6d4cf
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

config.tests/unix/floatmath/floatmath.cpp

@@ -33,7 +33,7 @@
 
 #include <math.h>
 
-int main(int argc, char **argv)
+int main(int, char **)
 {
     float c = ceilf(1.3f);
     float f = floorf(1.7f);