Fix type of variable used to store fgetc() result

fgetc() returns an int. Fix process_config_file() to store the result in
an int, so that comparisons against EOF succeed.

Previously, If "char" defaulted to unsigned (which may be true for armhf),
then when fgetc() returned -1, it would be truncated to 255 when stored
in the char, and then zero-filled rather than sign-extended when comparing
against EOF, which would then fail.

See http://code.google.com/p/chromium-os/issues/detail?id=25632.

Reported-by: Paul Fertser <fercerpav@gmail.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Change-Id: I018e32df9a87b7c6f9fe24d108e091a7b31a50c8
Reviewed-on: http://git-master/r/192151
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Allen Martin <amartin@nvidia.com>

parse.c

@@ -702,7 +702,7 @@ void process_config_file(build_image_context *context, u_int8_t simple_parse)
 {
 	char buffer[MAX_BUFFER];
 	int  space = 0;
-	char current;
+	int current;
 	u_int8_t c_eol_comment_start = 0; /* True after first slash */
 	u_int8_t comment = 0;
 	u_int8_t string = 0;