fix doxygen build

Update build rules to skip the PDF unless the TeX has been created.
Also, fixes a warning regarding pattern rules being a GNU make trick.

diff --git a/Makefile.am b/Makefile.am
index c06771204b218920a926ca9312d958a2b6347cf0..fab470466631b80ee1748d74a8b5a794f45e1939 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -35,9 +35,14 @@ THE_MANUAL = doxygen/latex/refman.pdf
 doxygen::
        $(MAKE) Doxyfile
        doxygen Doxyfile 2>&1 | perl $(srcdir)/tools/logger.pl > doxygen.log
-       $(MAKE) $(THE_MANUAL)
-
-%.pdf: %.tex
+       @if [ -f doxygen/latex/refman.tex ]; then \
+               echo "Creating $(THE_MANUAL)..."; \
+               $(MAKE) $(THE_MANUAL); \
+       else \
+               echo "Skipping Doxygen PDF..."; \
+       fi
+
+$(THE_MANUAL): %.pdf: %.tex
        -cd $$(dirname $*) && pdflatex $$(basename $*)
        -cd $$(dirname $*) && pdflatex $$(basename $*)