cmake: inline a few variables as needed

Avoid creating/appending variables and effectively deviating from the
style used across the project.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

src/gui/curses/normal/CMakeLists.txt

@@ -51,13 +51,9 @@ include_directories(.. ../../core ../../plugins ${NCURSES_INCLUDE_PATH})
 
 add_library(weechat_gui_curses_normal STATIC ${LIB_GUI_CURSES_SRC})
 
-set(WEECHAT_CURSES_MAIN_SRC main.c)
-
 set(EXECUTABLE weechat)
 
-add_executable(${EXECUTABLE} ${WEECHAT_CURSES_MAIN_SRC})
-
-list(APPEND EXTRA_LIBS ${NCURSES_LIBRARY})
+add_executable(${EXECUTABLE} main.c)
 
 target_link_libraries(${EXECUTABLE}
   weechat_core
@@ -65,6 +61,7 @@ target_link_libraries(${EXECUTABLE}
   weechat_gui_common
   weechat_gui_curses_normal
   ${EXTRA_LIBS}
+  ${NCURSES_LIBRARY}
   coverage_config
 )