Android: fix toolchain path retrieval for NDK r10

Although, recent Qt versions (Qt 5.12+) don't really need r10, this
can be useful if an older version is used, or if the user wants to
explicitly use Ndk r10.

Change-Id: Ic88929a747bcea89384a7bae9d8f8b26135fae65
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/android/androidconfigurations.cpp

@@ -473,7 +473,13 @@ FilePath AndroidConfig::avdManagerToolPath() const
 
 FilePath AndroidConfig::toolchainPathFromNdk(const Utils::FilePath &ndkLocation) const
 {
-    const FilePath toolchainPath = ndkLocation / "toolchains/llvm/prebuilt/";
+    const FilePath tcPath = ndkLocation / "toolchains/";
+    FilePath toolchainPath;
+    QDirIterator llvmIter(tcPath.toString(), {"llvm*"}, QDir::Dirs);
+    if (llvmIter.hasNext()) {
+        llvmIter.next();
+        toolchainPath = tcPath / llvmIter.fileName() / "prebuilt/";
+    }
 
     // detect toolchain host
     QStringList hostPatterns;