Build a minimized Nix with MinGW

At this point many features are stripped out, but this works:

- Can run libnix{util,store,expr} unit tests
- Can run some Nix commands

Co-Authored-By volth <volth@volth.com>
Co-Authored-By Brian McKenna <brian@brianmckenna.org>

src/libstore/schema.sql

@@ -1,42 +0,0 @@
-create table if not exists ValidPaths (
-    id               integer primary key autoincrement not null,
-    path             text unique not null,
-    hash             text not null, -- base16 representation
-    registrationTime integer not null,
-    deriver          text,
-    narSize          integer,
-    ultimate         integer, -- null implies "false"
-    sigs             text, -- space-separated
-    ca               text -- if not null, an assertion that the path is content-addressed; see ValidPathInfo
-);
-
-create table if not exists Refs (
-    referrer  integer not null,
-    reference integer not null,
-    primary key (referrer, reference),
-    foreign key (referrer) references ValidPaths(id) on delete cascade,
-    foreign key (reference) references ValidPaths(id) on delete restrict
-);
-
-create index if not exists IndexReferrer on Refs(referrer);
-create index if not exists IndexReference on Refs(reference);
-
--- Paths can refer to themselves, causing a tuple (N, N) in the Refs
--- table.  This causes a deletion of the corresponding row in
--- ValidPaths to cause a foreign key constraint violation (due to `on
--- delete restrict' on the `reference' column).  Therefore, explicitly
--- get rid of self-references.
-create trigger if not exists DeleteSelfRefs before delete on ValidPaths
-  begin
-    delete from Refs where referrer = old.id and reference = old.id;
-  end;
-
-create table if not exists DerivationOutputs (
-    drv  integer not null,
-    id   text not null, -- symbolic output id, usually "out"
-    path text not null,
-    primary key (drv, id),
-    foreign key (drv) references ValidPaths(id) on delete cascade
-);
-
-create index if not exists IndexDerivationOutputs on DerivationOutputs(path);