Common: Move floating-point utility functions to FloatUtils.h/.cpp

Keeps all of the floating-point utility functions in their own file to
keep them all together. This also provides a place for other
general-purpose floating-point functions to be added in the future,
which will be necessary when improving the flag-setting within the
interpreter.

Source/Core/Common/CMakeLists.txt

@@ -14,6 +14,7 @@ add_library(common
   File.cpp
   FileSearch.cpp
   FileUtil.cpp
+  FloatUtils.cpp
   GekkoDisassembler.cpp
   Hash.cpp
   HttpRequest.cpp