Android: Extra search directory to find make on windows

The sdk should set that extra directory, via the sdktool.

E. g. something like
sdktool addKeys android MakeExtraSearchDirectory QString:%DIRECTORY%

where %DIRECTORY% is the bin directory of the bundled mingw.
That is Tools\MinGW\bin for the qt sdk.

Also see:
Task-number: QTCREATORBUG-9297

Change-Id: I487c67b7fb704dd00cf5c6f4f647c8c4fbe8cd3d
Reviewed-by: Ray Donnelly <mingw.android@gmail.com>
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>

src/plugins/android/androidconfigurations.h

@@ -32,6 +32,7 @@
 
 #include <QObject>
 #include <QString>
+#include <QStringList>
 #include <QVector>
 #include <projectexplorer/abi.h>
 
@@ -55,6 +56,7 @@ public:
     Utils::FileName openJDKLocation;
     Utils::FileName keystoreLocation;
     QString toolchainHost;
+    QStringList makeExtraSearchDirectories;
     unsigned partitionSize;
     bool automaticKitCreation;
 };
@@ -97,6 +99,8 @@ public:
     QString startAVD(int *apiLevel, const QString &name = QString()) const;
     QString bestMatch(const QString &targetAPI) const;
 
+    QStringList makeExtraSearchDirectories() const;
+
     static ProjectExplorer::Abi::Architecture architectureForToolChainPrefix(const QString &toolchainprefix);
     static QLatin1String toolchainPrefix(ProjectExplorer::Abi::Architecture architecture);
     static QLatin1String toolsPrefix(ProjectExplorer::Abi::Architecture architecture);