Adds FAQ entries for VTK build problems on Ubuntu 16.04 with VTK6 ins…

…talled (RobotLocomotion#4901)

* Adds FAQ entries for VTK build problems on Ubuntu 16.04 with VTK6 installed.

* Update external/vtk origin URL to point to liang's fork and updated the SHA to include GLX_GLXEXT_LEGACY fix.

Updated SHA.

* Added note that VTK_DIR can be used to point to location of VTK5.

.gitmodules

@@ -113,4 +113,4 @@
 	url = https://github.com/patmarion/QtPropertyBrowser
 [submodule "externals/vtk"]
 	path = externals/vtk
-	url = git://vtk.org/VTK.git
+	url = https://github.com/liangfok/VTK.git

drake/doc/faq.rst

@@ -8,6 +8,43 @@ Frequently Asked Questions
    :depth: 3
    :local:
 
+.. _faq_cmake_vtk_version_crash:
+
+Why Does CMake Fail With An Error Indicating No Compatible VTK Found?
+=====================================================================
+
+Symptom: When running ``cmake ..`` in ``drake-distro/build``, the following
+error is reported::
+
+    CMake Error at cmake/options.cmake:172 (find_package):
+      Could not find a configuration file for package "VTK" that is compatible
+      with requested version "5.10".
+
+      The following configuration files were considered but not accepted:
+
+        /usr/lib/cmake/vtk-6.2/VTKConfig.cmake, version: 6.2.0
+
+    Call Stack (most recent call first):
+      cmake/options.cmake:249 (drake_system_dependency)
+      CMakeLists.txt:17 (drake_setup_options)
+
+
+    -- Configuring incomplete, errors occurred!
+
+Solution: This error is typically caused by your system having a newer version
+of VTK installed than the version required by Drake. As indicated by the error
+message, Drake needs VTK 5.10 whereas the system has VTK 6.2. To get around this
+error, add ``-DUSE_SYSTEM_VTK=OFF -DWITH_VTK=ON`` to the ``cmake`` command::
+
+    cd drake-distro/build
+    cmake .. -DUSE_SYSTEM_VTK=OFF -DWITH_VTK=ON
+
+Alternatively, if you have a compatible version of VTK5 installed, you can tell
+CMake to use it by specifying ``VTK_DIR`` as follows::
+
+    cd drake-distro/build
+    cmake .. -DVTK_DIR=path/to/vtk5
+
 .. _faq_vmware:
 
 Why doesn't Drake Visualizer work in VMWare Fusion or Workstation?