Clean up various warnings when building under -Wall Add some gimmicks to prevent fread() and fwrite() warnings about ignoring the return value. Yes, this is probably not a good thing to do, but doing something with a non-success return value is going to involve crashing out or something anyway. Also fix several warnings about variables used while possibly uninitialized. The code flow shows that this cannot be the case but initializing them to a plausible value at declaration time costs pretty much nothing and it makes gcc happy. Also caught a use of | instead of || which probably would have caused a certain check for duplicate declarations in __os9 sections to behave oddly.

--- a/lwlink/output.c	Tue Feb 05 22:39:34 2013 -0700
+++ b/lwlink/output.c	Wed Feb 06 21:43:10 2013 -0700
@@ -30,7 +30,8 @@
 // this prevents warnings about not using the return value of fwrite()
 // and, theoretically, can be replaced with a function that handles things
 // better in the future
-#define writebytes(s, l, c, f)	do { int r; r = fwrite((s), (l), (c), (f)); } while (0)
+//#define writebytes(s, l, c, f)	do { int r; r = fwrite((s), (l), (c), (f)); (void)r; } while (0)
+#define writebytes(s, l, c, f)	do { (void)(fwrite((s), (l), (c), (f)) && 1); } while (0)
 
 void do_output_os9(FILE *of);
 void do_output_decb(FILE *of);