[PATCH -perfbook 1/2] qqz.sty: Work around orphaned section heading

In ebook-size builds, tcolorbox occasionally complains:

    Package tcolorbox Warning: Using nobreak failed. Try to enlarge
    `lines before break' or set page breaks manually on input line
    xxxx.

This warning is accompanied by an unfortunate page/column break just
below a section heading in Appendix E.

Make such ugly breaks less likely by enclosing the \section command
with a pair of pagebreak/nopagebreak hints.

Signed-off-by: Akira Yokosawa <[email protected]>
--
You need to be very lucky to observe this issue.  At the moment,
you can observe it in perfbook-ebsf.pdf built on Ubuntu 22.04.
Section E.18's heading goes to the bottom of page 1277.

This change makes it go to the top of page 1278.
--
 qqz.sty | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/qqz.sty b/qqz.sty
index 5c7eb5340194..74ee0566b1c2 100644
--- a/qqz.sty
+++ b/qqz.sty
@@ -223,8 +223,9 @@
 %% Internal interfaces generated by scripts.
 
 \newcommand{\QuickQAC}[3]{
+	\pagebreak[3]
 	\edef\QuickQuizAnswerChapter{\getrefnumber{#1}}
-	\section{#2}}
+	\section{#2}\nopagebreak}
 
 \IfNoQqz{
 \newcommand{\QuickQQC}[3]{

base-commit: 54b77242aac76979b8bbb832809b55736167bf5e
-- 
2.25.1