tests: Fix static storage initializations

make[2]: Entering directory `/home/tiago/git/libyami/tests'
gcc -DHAVE_CONFIG_H -I. -I.. -I.. -I.. -I../interface -I/home/tiago/install/include     -I.. -I../interface -I/home/tiago/install/include    -g3 -O0 -MT gles2_help.o -MD -MP -MF .deps/gles2_help.Tpo -c -o gles2_help.o `test -f './egl/gles2_help.c' || echo './'`./egl/gles2_help.c
./egl/gles2_help.c: In function ‘drawTextures’:
./egl/gles2_help.c:171:5: error: initializer element is not constant
     static int rectSize1 = maxRectSize;
     ^
./egl/gles2_help.c:172:5: error: initializer element is not constant
     static int rectSize2 = minRectSize;
     ^
tests: Improve output messages in case of error