Updated depend.cmake to follow CMake IF convention.

Change-Id: I1e86cf134d3f40852033ae73f36d9143b389a918
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index dfe5589..c0b4ec0 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -54,7 +54,7 @@
                simple_bundle_adjuster.cc)
 TARGET_LINK_LIBRARIES(simple_bundle_adjuster ceres)
 
-IF (${GFLAGS})
+IF (GFLAGS)
   ADD_EXECUTABLE(nist nist.cc)
   TARGET_LINK_LIBRARIES(nist ceres)
 
@@ -70,5 +70,5 @@
                  denoising.cc
                  fields_of_experts.cc)
   TARGET_LINK_LIBRARIES(denoising ceres)
-ENDIF (${GFLAGS})
+ENDIF (GFLAGS)