Andrey Pokrovskiy authored Jan 20, 2016 and Brad King committed Jan 21, 2016

Refactoring merged by commit 9afbb733 (Merge topic
'use-generator-target', 2015-10-20) in and around commit 381e7afd
(cmExportSet: Store a cmGeneratorTarget, 2015-10-17) forgot to update
one place in this method.  This leads to a crash in code such as

  add_library(A a.c)
  add_library(B b.c)
  target_link_libraries(B A)
  install(TARGETS B DESTINATION lib EXPORT ExpB)
  install(EXPORT ExpB DESTINATION lib/cmake/test)
  add_executable(C c.c)
  install(TARGETS C DESTINATION bin EXPORT ExpC)

Fix the target name reference to avoid using an unpopulated Target
pointer.