[0.4.8][CYLFRAC] Fix 3 MSVC2010SP1 x86 dbg warnings C4305 CORE-18104

[0.4.8][CYLFRAC] Fix 3 MSVC2010SP1 x86 dbg warnings C4305 CORE-18104

can be observed with MSVC 2010SP1 (16.0.40219.1) x86 target in dbg configuration:
C:\047rls\reactos\modules\rosapps\applications\screensavers\cylfrac\cylfrac.c(109) : warning C4305: 'function' : truncation from 'double' to 'float'
C:\047rls\reactos\modules\rosapps\applications\screensavers\cylfrac\cylfrac.c(110) : warning C4305: 'function' : truncation from 'double' to 'float'
C:\047rls\reactos\modules\rosapps\applications\screensavers\cylfrac\cylfrac.c(137) : warning C4305: 'initializing' : truncation from 'double' to 'GLfloat'

partial pick of 0.4.15-dev-2951-g 5d8e834897781944dcaf80de6c3df9c2c51212c7