Install ares_dns.h too

ares/CHANGES

   Changelog for the c-ares project
 
+* November 22
+
+- Install ares_dns.h too
+
 * November 6
 
 - Yang Tse removed a couple of potential zero size memory allocations.

ares/Makefile.am

@@ -59,7 +59,7 @@ libcares_la_SOURCES = $(CSOURCES) $(HHEADERS)
 # where to install the c-ares headers
 libcares_ladir = $(includedir)
 # what headers to install on 'make install':
-libcares_la_HEADERS = ares.h ares_version.h
+libcares_la_HEADERS = ares.h ares_version.h ares_dns.h
 
 # Make files named *.dist replace the file without .dist extension
 dist-hook: