build: fix building with coverage report

Both ${SHELL_APP} variable and the target with that name is defined
later in the CMakeLists.txt, so the coverage enabling code has to move
down.

CMakeLists.txt

@@ -24,21 +24,6 @@ if(cmake_build_type_lower MATCHES "debug")
 endif()
 
 find_package(CoverageReport)
-#####################################################################
-# Enable code coverage calculation with gcov/gcovr/lcov
-# Usage:
-#  * Switch build type to coverage (use ccmake or cmake-gui)
-#  * Invoke make, make test, make coverage (or ninja if you use that backend)
-#  * Find html report in subdir coveragereport
-#  * Find xml report feasible for jenkins in coverage.xml
-#####################################################################
-if(cmake_build_type_lower MATCHES coverage)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --coverage" )
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} --coverage" )
-  set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} --coverage" )
-  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} --coverage" )
-  ENABLE_COVERAGE_REPORT(TARGETS ${SHELL_APP} FILTER /usr/include ${CMAKE_SOURCE_DIR}/tests/* ${CMAKE_BINARY_DIR}/*)
-endif()
 
 find_package (ECM 1.7.0 QUIET NO_MODULE)
 if (ECM_FOUND)
@@ -190,6 +175,22 @@ else()
     message(STATUS "Tests disabled")
 endif()
 
+#####################################################################
+# Enable code coverage calculation with gcov/gcovr/lcov
+# Usage:
+#  * Switch build type to coverage (use ccmake or cmake-gui)
+#  * Invoke make, make test, make coverage (or ninja if you use that backend)
+#  * Find html report in subdir coveragereport
+#  * Find xml report feasible for jenkins in coverage.xml
+#####################################################################
+if(cmake_build_type_lower MATCHES coverage)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --coverage" )
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} --coverage" )
+  set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} --coverage" )
+  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} --coverage" )
+  ENABLE_COVERAGE_REPORT(TARGETS ${SHELL_APP} FILTER /usr/include ${CMAKE_SOURCE_DIR}/tests/* ${CMAKE_BINARY_DIR}/*)
+endif()
+
 add_subdirectory(plugins)
 
 #