Don't name std::fmodf.

[BillyONeal]

The C standard library function fmodf is not guaranteed to be in namespace std, and in fact is not with a default Ubuntu 24.04 installation, leading to the following compile error:

Change Dir: '/vcpkg/buildtrees/vcpkg-ci-orange-math/x64-linux-dbg'

Run Build Command(s): /vcpkg/downloads/tools/ninja/1.12.1-linux/ninja -v -v -j33
[1/2] /usr/bin/c++ -DOMATH_SUPRESS_SAFETY_CHECKS -DOMATH_VERSION=\"3.5.0\" -isystem /vcpkg/installed/x64-linux/include -fPIC -g -std=gnu++23 -MD -MT CMakeFiles/main.dir/main.cpp.o -MF CMakeFiles/main.dir/main.cpp.o.d -o CMakeFiles/main.dir/main.cpp.o -c /vcpkg/scripts/test_ports/vcpkg-ci-orange-math/project/main.cpp
FAILED: CMakeFiles/main.dir/main.cpp.o
/usr/bin/c++ -DOMATH_SUPRESS_SAFETY_CHECKS -DOMATH_VERSION=\"3.5.0\" -isystem /vcpkg/installed/x64-linux/include -fPIC -g -std=gnu++23 -MD -MT CMakeFiles/main.dir/main.cpp.o -MF CMakeFiles/main.dir/main.cpp.o.d -o CMakeFiles/main.dir/main.cpp.o -c /vcpkg/scripts/test_ports/vcpkg-ci-orange-math/project/main.cpp
In file included from /vcpkg/installed/x64-linux/include/omath/omath.hpp:22,
                 from /vcpkg/scripts/test_ports/vcpkg-ci-orange-math/project/main.cpp:1:
/vcpkg/installed/x64-linux/include/omath/color.hpp: In member function ‘constexpr omath::Hsv omath::Color::to_hsv() const’:
/vcpkg/installed/x64-linux/include/omath/color.hpp:98:45: error: ‘fmodf’ is not a member of ‘std’; did you mean ‘modf’?
   98 |                 hsv_data.hue = 60.f * (std::fmodf(((green - blue) / delta), 6.f));
      |                                             ^~~~~
      |                                             modf
ninja: build stopped: subcommand failed.

Only the 'sufficient additional overloads' of fmod are guaranteed to be in std. Since this is clearly intended to call the (float, float) overload, explicitly cast ((green - blue) / delta) (which is a double) to float and call the name in std as suggested by the diagnostic.

[BillyONeal]

https://eel.is/c++draft/cmath.syn

I observe that current versions of C++ do explicitly name constexpr float fmodf(float x, float y); so it's possible that this situation may be changed in more recent toolchains than those bundled on the test Ubuntu 24.04 system. Or something else funny may be going on because this is in the "WG21 wanted to touch WG14's header" <math.h>/<cmath> mess ...

[orange-cpp]

thx for pl