coverage: make errors fatal

cmake/commons/CoverageFunction.cmake

@@ -22,31 +22,31 @@ find_program(GENHTML_COMMAND genhtml)
 if(GCOV_COMMAND)
     set(CMAKE_GCOV_FOUND TRUE)
 else()
-    message(ERROR "could not locate gcov executable, cannot add code coverage custom target!")
+    message(FATAL_ERROR "could not locate gcov executable, cannot add code coverage custom target!")
 endif()
 
 if(LCOV_COMMAND)
     set(CMAKE_LCOV_FOUND TRUE)
 else()
-    message(ERROR "could not locate lcov executable, cannot add code coverage custom target!")
+    message(FATAL_ERROR "could not locate lcov executable, cannot add code coverage custom target!")
 endif()
 
 if(GENHTML_COMMAND)
     set(CMAKE_GENHTML_FOUND TRUE)
 else()
-    message(ERROR "could not locate genhtml executable, cannot add code coverage custom target!")
+    message(FATAL_ERROR "could not locate genhtml executable, cannot add code coverage custom target!")
 endif()
 
 if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
     string(APPEND CMAKE_C_FLAGS " -coverage")
 else()
-    message(ERROR "C compiler is not GNU; don't know how to set code coverage flags!")
+    message(FATAL_ERROR "C compiler is not GNU; don't know how to set code coverage flags!")
 endif()
 
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     string(APPEND CMAKE_CXX_FLAGS " -coverage")
 else()
-    message(ERROR "CXX compiler is not GNU; don't know how to set code coverage flags!")
+    message(FATAL_ERROR "CXX compiler is not GNU; don't know how to set code coverage flags!")
 endif()
 
 # function to add a coverage target