Install dev headers only if --with-dev-headers= option is set

src/libfast/Makefile.am

@@ -3,9 +3,11 @@ ipseclib_LTLIBRARIES = libfast.la
 libfast_la_SOURCES = \
 	dispatcher.c request.c session.c smtp.c
 
-fast_includedir = $(includedir)/strongswan/fast
+if USE_DEV_HEADERS
+fast_includedir = ${dev_headers}/fast
 nobase_fast_include_HEADERS = \
 	context.h controller.h dispatcher.h filter.h request.h session.h smtp.h
+endif
 
 libfast_la_LIBADD = $(top_builddir)/src/libstrongswan/libstrongswan.la \
   -lfcgi $(clearsilver_LIBS) $(PTHREADLIB)