REG: Fix make install on library projects on Android

This is a partial revert of 39e04b0222.
The original change moved the special make install target path logic
into the logic for the app template to make it possible to remove the
condition that excluded builds inside the Qt directory. This was
to make it possible to build examples in the Qt directory for Android
without moving them. However, this broke user library projects,
specifically when they were part of a subdirs project and should
have been automatically installed into the Android package. This
patch brings back the logic but only enables it for library projects,
meaning that the only examples inside Qt which cannot be built
correctly are library projects (which didn't work anyway).

[ChangeLog][Android] Fixed regression in "make install" on
library projects on Android so they can be used inside subdirs
projects again.

Task-number: QTBUG-34781
Change-Id: Iabf53ed68845b2ddd4ae66656e1372c96185660e
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

mkspecs/features/android/android.prf

@@ -8,4 +8,7 @@ contains(TEMPLATE, ".*app") {
             INSTALLS *= target
         }
     }
+} else: contains(TEMPLATE, "lib"):!QTDIR_build:android_install {
+    target.path = /libs/$$ANDROID_TARGET_ARCH/
+    INSTALLS *= target
 }