[svn-r9988] Purpose:

Bug fix

Description:
pmake (on modi4, for instance) complains about undefined variables
if it is run without the -V flag, which turns those errors to warnings.

Solution:
Added test to configure.in to see if $MAKE will allow Makefiles
with undefined variables.  If not, sets -V flag in AM_MAKEFLAGS.
Ensured that all custom make targets use AM_MAKEFLAGS.
Also defined all variables that caused errors in top-level Makefile.am.
This means that pmake can be used to build hdf5 *from the top level
only*.  To run make from a subdirectory, still need to use -V flag
(or use make or gmake).

Platforms tested:
modi4, heping, copper, sleipnir

config/commence-doc.am

@@ -1,3 +1,4 @@
+## config/commence-doc.am
 ## This file supplies Makefile.am files in the doc directory (and subdirectories)
 ## with the rules they need.
 
@@ -9,13 +10,13 @@ lib progs check test _test:
 
 tests dep depend:
 	@@SETX@; for d in X $(SUBDIRS); do                                  \
-	  if test $$d != X; then                                              \
-	    (cd $$d && $(MAKE) $@) || exit 1;                                 \
+	  if test $$d != X; then                                            \
+	    (cd $$d && $(MAKE) $(AM_MAKEFLAGS) $@) || exit 1;               \
 	  fi;     
 	done
 
 # In docs directory, install-doc is the same as install
 install-doc install-all:
-	$(MAKE) install
+	$(MAKE) $(AM_MAKEFLAGS) install
 uninstall-doc uninstall-all:
-	$(MAKE) uninstall
+	$(MAKE) $(AM_MAKEFLAGS) uninstall