Rollup merge of #149554 - mati865:build-manifest-more-gen, r=Mark-Simulacrum

build-manifest: generate MSI and MINGW arrays from rustc

An alternative to #149503

The arrays after generating:
```
❯ bat -n build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/build/build-manifest-e0236666c7c4187b/out/targets.rs | rg MSI -A14
 136 static MSI_INSTALLERS: &[&str] = &[
 137     "aarch64-pc-windows-gnullvm",
 138     "aarch64-pc-windows-msvc",
 139     "i686-pc-windows-gnu",
 140     "i686-pc-windows-msvc",
 141     "x86_64-pc-windows-gnu",
 142     "x86_64-pc-windows-gnullvm",
 143     "x86_64-pc-windows-msvc",
 144 ];
 145 static MINGW: &[&str] = &[
 146     "aarch64-pc-windows-gnullvm",
 147     "i686-pc-windows-gnu",
 148     "x86_64-pc-windows-gnu",
 149     "x86_64-pc-windows-gnullvm",
 150 ];
```

r? `@Mark-Simulacrum`

Author: Zalathar

src/tools/build-manifest/build.rs

@@ -60,7 +60,7 @@ fn main() {
     let mut output = String::new();
 
     writeln!(output, "static HOSTS: &[&str] = &[").unwrap();
-    for host in targets.hosts {
+    for host in &targets.hosts {
         writeln!(output, "    {:?},", host).unwrap();
     }
     writeln!(output, "];").unwrap();
@@ -71,6 +71,22 @@ fn main() {
     }
     writeln!(output, "];").unwrap();
 
+    writeln!(output, "static MSI_INSTALLERS: &[&str] = &[").unwrap();
+    for host in &targets.hosts {
+        if host.contains("-windows-") {
+            writeln!(output, "    {:?},", host).unwrap();
+        }
+    }
+    writeln!(output, "];").unwrap();
+
+    writeln!(output, "static MINGW: &[&str] = &[").unwrap();
+    for host in targets.hosts {
+        if host.contains("-windows-gnu") {
+            writeln!(output, "    {:?},", host).unwrap();
+        }
+    }
+    writeln!(output, "];").unwrap();
+
     std::fs::write(PathBuf::from(std::env::var_os("OUT_DIR").unwrap()).join("targets.rs"), output)
         .unwrap();
 }

src/tools/build-manifest/src/main.rs

@@ -29,18 +29,8 @@ static DOCS_FALLBACK: &[(&str, &str)] = &[
     ("", "x86_64-unknown-linux-gnu"),
 ];
 
-static MSI_INSTALLERS: &[&str] = &[
-    "aarch64-pc-windows-msvc",
-    "i686-pc-windows-gnu",
-    "i686-pc-windows-msvc",
-    "x86_64-pc-windows-gnu",
-    "x86_64-pc-windows-msvc",
-];
-
 static PKG_INSTALLERS: &[&str] = &["x86_64-apple-darwin", "aarch64-apple-darwin"];
 
-static MINGW: &[&str] = &["i686-pc-windows-gnu", "x86_64-pc-windows-gnu"];
-
 static NIGHTLY_ONLY_COMPONENTS: &[PkgType] =
     &[PkgType::Miri, PkgType::JsonDocs, PkgType::RustcCodegenCranelift];