fix misspelling in comment

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/libbb/getopt32.c b/libbb/getopt32.c
index eb99800..25bae31 100644
--- a/libbb/getopt32.c
+++ b/libbb/getopt32.c
@@ -115,7 +115,7 @@
         found.
 
  "ww"   Adjacent double options have a counter associated which indicates
-        the number of occurences of the option.
+        the number of occurrences of the option.
         For example the ps applet needs:
         if w is given once, GNU ps sets the width to 132,
         if w is given more than once, it is "unlimited"