[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/conclude.am

@@ -1,8 +1,6 @@
-#------------------------------------------------------------ -*- makefile -*-
-# The following section of this makefile comes from the
-# `./config/conclude' file which was generated with config.status
-# from `./config/conclude.in'.
-#-----------------------------------------------------------------------------
+## config/conclude.am
+## Textually included at the end of most HDF5 Makefiles.am.
+## Contains build rules.
 
 # Automake needs to be taught how to build lib, progs, and tests targets.
 # These will be filled in automatically for the most part (e.g.,
@@ -23,10 +21,10 @@ build-progs: $(LIB) $(PROGS)
 build-tests: $(LIB) $(PROGS) $(TESTS)
 
 lib progs tests ::
-	@$(MAKE) build-$@ || exit 1;                                          \
+	@$(MAKE) $(AM_MAKEFLAGS) build-$@ || exit 1;                          \
 	for d in X $(SUBDIRS); do                                             \
 	    if test $$d != X -a $$d != .; then                                \
-	        (set -x; cd $$d && $(MAKE) $@) || exit 1;                     \
+	        (set -x; cd $$d && $(MAKE) $(AM_MAKEFLAGS) $@) || exit 1;     \
 	    fi;                                                               \
 	done
 
@@ -133,6 +131,6 @@ check-vfd:
 	        echo "============================";                          \
 	        echo "Testing Virtual File Driver $$vfd";                     \
 	        echo "============================";                          \
-	        HDF5_DRIVER=$$vfd $(MAKE) check;                              \
+	        HDF5_DRIVER=$$vfd $(MAKE) $(AM_MAKEFLAGS) check;              \
 	    fi;                                                               \
 	done