zig libc: allow non-native targets

On macos, allow targets supported by the SDK. This then spawns `xcrun`
and correct paths are emitted for:

- x86_64-macos
- x86_64-ios
- x86_64-tvos
- x86_64-watchos
- x86_64-ios-macbi
- aarch64-macos
- aarch64-ios
- aarch64-tvos
- aarch64-watchos
- aarch64-ios-macbi

On platforms with android NDK, allow android targets. Example usage:

```
CC=/NDK/.../bin/aarch64-linux-android34-clang zig libc -target aarch64-linux-android
```

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/std/Target/Query.zig b/lib/std/Target/Query.zig
index e54ac0c3c6..d290e2a8d2 100644
--- a/lib/std/Target/Query.zig
+++ b/lib/std/Target/Query.zig
@@ -415,6 +415,15 @@ pub fn isNative(self: Query) bool {
     return self.isNativeCpu() and self.isNativeOs() and self.isNativeAbi();
 }
 
+pub fn canDetectLibC(self: Query) bool {
+    if (self.isNative()) return true;
+    if (self.os_tag) |os| {
+        if (builtin.os.tag == .macos and os.isDarwin()) return true;
+        if (os == .linux and self.abi == .android) return true;
+    }
+    return false;
+}
+
 /// Formats a version with the patch component omitted if it is zero,
 /// unlike SemanticVersion.format which formats all its version components regardless.
 fn formatVersion(version: SemanticVersion, writer: anytype) !void {