Prefer helper functions to identify MinGW targets

Author: mati865

src/bootstrap/src/core/build_steps/dist.rs

@@ -347,14 +347,14 @@ fn runtime_dll_dist(rust_root: &Path, target: TargetSelection, builder: &Builder
 
     let mut rustc_dlls = vec![];
     // windows-gnu and windows-gnullvm require different runtime libs
-    if target.ends_with("windows-gnu") {
+    if target.is_windows_gnu(){
         rustc_dlls.push("libwinpthread-1.dll");
         if target.starts_with("i686-") {
             rustc_dlls.push("libgcc_s_dw2-1.dll");
         } else {
             rustc_dlls.push("libgcc_s_seh-1.dll");
         }
-    } else if target.ends_with("windows-gnullvm") {
+    } else if target.is_windows_gnullvm() {
         rustc_dlls.push("libunwind.dll");
     } else {
         panic!("Vendoring of runtime DLLs for `{target}` is not supported`");

src/bootstrap/src/core/build_steps/llvm.rs

@@ -284,7 +284,7 @@ impl Step for Llvm {
             LlvmBuildStatus::ShouldBuild(m) => m,
         };
 
-        if builder.llvm_link_shared() && target.is_windows() && !target.ends_with("windows-gnullvm")
+        if builder.llvm_link_shared() && target.is_windows() && !target.is_windows_gnullvm()
         {
             panic!("shared linking to LLVM is not currently supported on {}", target.triple);
         }