Clean up compiler warnings:

* bcache.h, bcache.c, c-valprint.c, coffread.c, stabsread.c,
	stack.c, valprint.c: Change variables to unsigned.
	* bcache.c: Rearrange to avoid warnings about variables not being set.
	* c-lang.c, ch-lang.c, f-lang.c, m2-lang.c: Include valprint.h
	rather than declaring print_max and repeat_count_threashold
	ourselves (incorrectly).
	* valprint.h: Do declare repeat_count_threashold.
	* ch-exp.c: Use default case for internal error.
	* findvar.c: Don't omit argument type.
	* symtab.c: Remove unused variable.

gdb/ch-exp.c

@@ -2192,8 +2192,8 @@ ch_lex ()
 	    case LOC_OPTIMIZED_OUT:
 	      error ("Symbol \"%s\" names no location.", inputname);
 	      break;
-	    case LOC_UNRESOLVED:
-	      error ("unhandled SYMBOL_CLASS in ch_lex()");
+	    default:
+	      internal_error ("unhandled SYMBOL_CLASS in ch_lex()");
 	      break;
 	    }
 	}