[cmake] use full path in headercheck target names, fixes #177

cmake/DuneUtils.cmake

@@ -42,7 +42,7 @@ ENDMACRO(INCLUDE_SYS_DIR)
 MACRO( HEADERCHECK )
 	ADD_CUSTOM_TARGET( headercheck SOURCES ${ARGN} )
 	FOREACH( HEADER ${ARGN} )
-		GET_FILENAME_COMPONENT( fn ${HEADER} NAME )
+		string(REPLACE "/" "_" fn ${HEADER})	
 		SET( TEST_NAME "headercheck_${fn}")
 		TO_LIST_SPACES( MY_CXX_FLAGS TEST_NAME_FLAGS )
 		SET(XARGS ${TEST_NAME_FLAGS} -DHAVE_CONFIG_H -c ${HEADER} -o ${CMAKE_CURRENT_BINARY_DIR}/${TEST_NAME}.o )