CODING_STYLE: Fix a typo ("have" vs. "has")

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff --git a/CODING_STYLE b/CODING_STYLE
index e7fde15..f53180b 100644
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -9,7 +9,7 @@
 Of course, the most important aspect in any coding style is whitespace.
 Crusty old coders who have trouble spotting the glasses on their noses
 can tell the difference between a tab and eight spaces from a distance
-of approximately fifteen parsecs.  Many a flamewar have been fought and
+of approximately fifteen parsecs.  Many a flamewar has been fought and
 lost on this issue.
 
 QEMU indents are four spaces.  Tabs are never used, except in Makefiles