doxygen docs: automatically update lib version

configure.ac

@@ -2009,6 +2009,7 @@ po/configure.acT:po/configure.ac.in
 Makefile
 contrib/Makefile
 doc/Makefile
+doc/doxygen/libmicrohttpd.doxy
 doc/doxygen/Makefile
 doc/examples/Makefile
 m4/Makefile

doc/doxygen/libmicrohttpd.doxy → doc/doxygen/libmicrohttpd.doxy.in

@@ -38,7 +38,7 @@ PROJECT_NAME           = "GNU libmicrohttpd"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 0.9.29
+PROJECT_NUMBER         = @PACKAGE_VERSION@
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a