[CMake] no need to check for BUILD_GTK_TESTS for single tests

poppler_add_test(... BUILD_GTK_TESTS ...) takes care of that already
diff --git a/glib/CMakeLists.txt b/glib/CMakeLists.txt
index 7a6548f..92a867e 100644
--- a/glib/CMakeLists.txt
+++ b/glib/CMakeLists.txt
@@ -93,11 +93,11 @@
 )
 
 
-if (GDK_FOUND AND BUILD_GTK_TESTS)
+if (GDK_FOUND)
   set(test_poppler_glib_SRCS
     test-poppler-glib.cc
   )
   poppler_add_test(test-poppler-glib BUILD_GTK_TESTS ${test_poppler_glib_SRCS})
   target_link_libraries(test-poppler-glib poppler-glib ${GDK2_LIBRARIES})
-endif (GDK_FOUND AND BUILD_GTK_TESTS)
+endif (GDK_FOUND)
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 0c01418..acb867b 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -15,7 +15,7 @@
 
 endif (ENABLE_SPLASH)
 
-if (GTK_FOUND AND BUILD_GTK_TESTS)
+if (GTK_FOUND)
 
   add_definitions(${GTK2_CFLAGS})
 
@@ -50,7 +50,7 @@
 
   endif (HAVE_CAIRO)
 
-endif (GTK_FOUND AND BUILD_GTK_TESTS)
+endif (GTK_FOUND)
 
 set (pdf_fullrewrite_SRCS
   pdf-fullrewrite.cc