Use pkgconfig to find ncurses libs in order to support separate libtinfo.

--- weechat-2.1/src/gui/curses/normal/CMakeLists.txt
+++ weechat-2.1/src/gui/curses/normal/CMakeLists.txt
@@ -29,7 +29,13 @@
   ../gui-curses-window.c
 )
 
-find_package(Ncurses)
+find_package(PkgConfig)
+pkg_search_module(NCURSES ncursesw ncurses)
+
+if(NOT NCURSES_FOUND)
+  find_package(Ncurses)
+endif(NOT NCURSES_FOUND)
+
 if(NCURSES_FOUND)
   check_include_files(ncursesw/ncurses.h NCURSESW_HEADERS)
   if(NCURSESW_HEADERS)
@@ -54,7 +60,7 @@
 
 add_dependencies(${EXECUTABLE} weechat_gui_curses_normal)
 
-list(APPEND EXTRA_LIBS ${NCURSES_LIBRARY})
+list(APPEND EXTRA_LIBS ${NCURSES_LIBRARY} ${NCURSES_LIBRARIES})
 
 # Due to circular references, we must link two times with libweechat_core.a and libweechat_gui_common.a
 target_link_libraries(${EXECUTABLE} ${STATIC_LIBS} weechat_gui_curses_normal ${EXTRA_LIBS} ${STATIC_LIBS})