videoUNICAP build fails on Linux due to undefined math functions

[avilleret]

I don't know why this happens but today when building videoUNICAP on Ubuntu 14.04 I got :

videoUNICAP.cpp: In function 'float {anonymous}::dimension_penalty(int, int, unicap_rect_t&)':
videoUNICAP.cpp:237:30: error: 'sqrt' was not declared in this scope
         double r=sqrt(w*w+h*h);
videoUNICAP.cpp:239:25: error: 'fabs' was not declared in this scope
         return fabs(r-r0);
videoUNICAP.cpp:242:26: error: 'sqrt' was not declared in this scope
         double r=sqrt(w*h);
videoUNICAP.cpp:244:25: error: 'fabs' was not declared in this scope
         return fabs(r-r0);
videoUNICAP.cpp:247:31: error: 'fabs' was not declared in this scope
       return fabs(w-size.width);
videoUNICAP.cpp:249:32: error: 'fabs' was not declared in this scope
       return fabs(h-size.height);