Unset the local version of BUILD_SHARED_LIBS that moab creates.

Certain version of MOAB will create a variable called BUILD_SHARED_LIBS that
will hide the cache version inside SMTK. This mean that if you are building
smtk shared and with a static moab, you will actually build smtk statically.

The fix is to remove the local version of the variable after importing
the moab config file.

CMake/FindMOAB.cmake

@@ -61,6 +61,12 @@ if(MOAB_FOUND)
       include(MOABTargets.cmake)
   endif()
 
+  #Certain version of moab define a scope variable called BUILD_SHARED_LIBS
+  #which hides the cache version of said variable. So we defend against
+  #this by unsetting the variable
+  unset(BUILD_SHARED_LIBS)
+
+
   set_target_properties(MOAB PROPERTIES
       INTERFACE_INCLUDE_DIRECTORIES "${MOAB_INCLUDE_DIR}"
       )