i've committed this initial fix based on Joel's feedback:

2011-12-31  Mike Frysinger  <vapier@gentoo.org>

    * configure.ac: Change AC_CHECK_LIB to AC_SEARCH_LIBS to match
    the code in gdb's configure.ac with $TERMCAP.
    * configure: Regenerated.

--- configure.ac	18 Oct 2011 00:30:57 -0000	1.6
+++ configure.ac	31 Dec 2011 06:58:27 -0000
@@ -17,7 +17,9 @@ lose
 if test x$sim_cv_os_cygwin = xyes; then
   TERMCAP='`if test -r ../../libtermcap/libtermcap.a; then echo ../../libtermcap/libtermcap.a; else echo -ltermcap; fi` -luser32'
 else
-  AC_CHECK_LIB(termcap, main, TERMCAP=-ltermcap, TERMCAP="")
+  # Keep in sync with gdb's configure.ac list.
+  AC_SEARCH_LIBS(tgetent, [termcap tinfo curses ncurses],
+    [TERMCAP=$ac_cv_search_tgetent], [TERMCAP=""])
 fi
 AC_SUBST(TERMCAP)
 
-mike