Add a few casts, fix compiler warnings on NetBSD 5

This fixes a few warnings of this type:
  XXX.c: In function 'AAA':
  XXX.c:YY: warning: array subscription has type 'char'

Tested on NetBSD 5.0.2 with gcc 4.1.3.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/tool/tool.c b/src/tool/tool.c
index eb6c131e..1bb3ebe6 100644
--- a/src/tool/tool.c
+++ b/src/tool/tool.c
@@ -84,7 +84,7 @@ ngt_UpperStr(char *String)
 
 	ptr = String;
 	while(*ptr) {
-		*ptr = toupper(*ptr);
+		*ptr = toupper((int)*ptr);
 		ptr++;
 	}
 	return String;
@@ -103,7 +103,7 @@ ngt_LowerStr(char *String)
 
 	ptr = String;
 	while(*ptr) {
-		*ptr = tolower(*ptr);
+		*ptr = tolower((int)*ptr);
 		ptr++;
 	}
 	return String;