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/valprint.c

@@ -684,7 +684,7 @@ print_binary_chars (stream, valaddr, len)
 #define BITS_IN_BYTES 8
 
   unsigned char *p;
-  int i;
+  unsigned int i;
   int b;
 
   /* Declared "int" so it will be signed.