winetest: Rename xmalloc() & co to heap_xxx() to not imply they are based on malloc(), and add heap_free().

oleaut32: Add a failing VarFormat test showing that wine wrongly truncates decimals with large negative exponents instead of rounding.

Fixes a memory leak on an error path. Found by Smatch.

Windows drivers do this as well and some apps rely on this (it might
fix Sketchup but I can't reproduce the issues on this system).

wgl: Duplicate some single buffered pixel formats for bitmap rendering and restrict bitmap rendering to these formats.

The use of direct / indirect rendering is now tied to the bitmapFormat
flag of a pixel format. Indirect is fine for bitmap rendering since on
windows it is only supported using the software gdi renderer and
indirect rendering can also indicate software rendering.

This was needed unconditionally in the past to apply fog, but since we're
using the ARBfp fog defines it is only needed if an sRGB correction is done
at the end of the shader.

msvfw32: Clearly separate the 16-bit code out of the rest by wrapping 16-bit message functions in thunks.

fusion: CompareAssemblyIdentity() and GetAssemblyIdentityFromFile() are unused stubs and don't belong in fusion.dll. So remove them.