symhandling followup for Linux

- tile2x11 would not build because drawing.c now depended on strcmpi which
was (via STRNCMPI not being defined) defined to strncmpi which is
implemented in hacklib.c which needs panic which is defined in... I gave up
on tracking down all the loose ends and changed the strcmpi to strcmp,
which means the handling is case sensitive, but it avoids a bunch of
changes to the way the util/Makefile.
- the symhandling changes introduced a chicken and the egg problem for
ASCIIGRAPH on Unix platforms, which was getting the defn from tcap.h but
that does not get included earlier enough nor often enough.  I added a defn
to unixconf.h to mimic ntconf.h, since ASCIIGRAPH is normally defined on Unix.
- options.c included an unused decl for a function named graphics_opts
- Unix Makefile was not installing "symbols".  I'm assuming this isn't
supposed to get the DLB treatment.

include/tcap.h

@@ -12,7 +12,7 @@
 #endif
 
 /* might display need graphics code? */
-#if !defined(AMIGA) && !defined(TOS) && !defined(MAC)
+#if !defined(AMIGA) && !defined(TOS) && !defined(MAC) && !defined(ASCIIGRAPH)
 # if defined(TERMLIB) || defined(OS2) || defined(MSDOS)
 #  define ASCIIGRAPH
 # endif

include/unixconf.h

@@ -56,6 +56,7 @@
 #define TEXTCOLOR	/* Use System V r3.2 terminfo color support */
 			/* and/or ANSI color support on termcap systems */
 			/* and/or X11 color */
+#define ASCIIGRAPH	/* ASCII graphics support on terminals */
 #define POSIX_JOB_CONTROL /* use System V / Solaris 2.x / POSIX job control */
 			/* (e.g., VSUSP) */
 #define POSIX_TYPES	/* use POSIX types for system calls and termios */