Fix the trivial compiler warnings in debugger/ when compiling with -W
- moved inline statements to front
- fixed the trivial cases of signed/unsigned comparisons

diff --git a/debugger/expr.c b/debugger/expr.c
index 3352c33..1051efa 100644
--- a/debugger/expr.c
+++ b/debugger/expr.c
@@ -106,7 +106,7 @@
 #define EXPR_TYPE_CAST		11
 
 static char expr_list[4096];
-static int next_expr_free = 0;
+static unsigned int next_expr_free = 0;
 
 /*
  * This is how we turn an expression address into the actual value.