CODING_STYLE: explicitly allow braceless 'else if'

It's already allowed by the example; there are about 1800 instances in the
tree; and disallowing it would lead to

    if (a) {
        ...
    } else {
        if (b) {
            ...
        } else {
            if (c) {
                ...
            } else {
                if (d) {
                    ...
                } else {
                    ...
                }
            }
        }
    }

instead of

    if (a) {
        ...
    } else if (b) {
        ...
    } else if (c) {
        ...
    } else if (d) {
        ...
    } else {
        ...
    }

which is more readable.
Acked-by: NBlue Swirl <blauwirbel@gmail.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

CODING_STYLE

@@ -68,6 +68,10 @@ keyword.  Example:
         printf("a was something else entirely.\n");
     }
 
+Note that 'else if' is considered a single statement; otherwise a long if/
+else if/else if/.../else sequence would need an indent for every else
+statement.
+
 An exception is the opening brace for a function; for reasons of tradition
 and clarity it comes on a line by itself: