windows: Make msvc __readeflags more readable

windows: Make msvc __readeflags more readable

Semicolon in msvc __asm block means start of the comment, and not end of
the __asm statement, like it is for all other C statements. Also function
which uses msvc inline assembly cannot be inlined to another function
(compiler reports a warning about it, not a fatal error). So add explicit
curly brackets for __asm block, remove misleading semicolons and do not
declare function as inline.