Fix #17486 - mmsystem header has align(1): near top

[0-v-0]

No description provided.

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[rikkimax]

This looks to be required.

https://github.com/tpn/winsdk-10/blob/master/Include/10.0.16299.0/um/mmsystem.h#L36

[0-v-0]

align(1): inside the struct differs from outside the struct.

struct A {
align(1):
	ubyte x;
	int y;
}
pragma(msg, A.sizeof);
pragma(msg, A.y.offsetof);
align(1):
struct B {
	ubyte x;
	int y;
}
pragma(msg, B.sizeof);
pragma(msg, B.y.offsetof);

outputs 5,1,8,4