* Output refman.log in case of build error.

doc/Makefile.am

@@ -29,7 +29,7 @@ if USE_LATEX
 	rm -f latex/libcaca.tex latex/libcaca.pdf
 	mv latex/refman.tex latex/libcaca.tex
 	sed 's/setlength{/renewcommand{/' latex/libcaca.tex > latex/refman.tex
-	cd latex && $(MAKE) $(AM_CFLAGS) refman.pdf
+	cd latex && $(MAKE) $(AM_CFLAGS) refman.pdf || (cat refman.log; exit 1)
 	mv latex/refman.pdf latex/libcaca.pdf
 	touch stamp-latex
 endif